What is the kinetic energy of the emitted electrons when cesium is exposed to uv rays of frequency 1.9×1015hz? express your answer in joules to three significant figures?
Final answer:
The kinetic energy of the emitted electrons when cesium is exposed to UV rays of frequency 1.9 × 10¹⁵ Hz is approximately 9.51 × 10⁻¹⁹ J.
Explanation:
To find the kinetic energy of the emitted electrons, we need to use the equation:
Kinetic Energy (KE) = Energy of the photon - Work Function
The energy of a photon can be calculated using the equation:
Energy (E) = Planck's constant (h) × frequency (f)
Given that the frequency of the UV rays is 1.9 × 1015 Hz, we can calculate the energy of the photon. The value of Planck's constant is 6.626 × 10-34 J·s.
Let's calculate the energy:
E = (6.626 × 10-34 J·s) × (1.9 × 1015 Hz) = 1.2594 × 10-18 J
Now we need to find the work function of cesium, which represents the minimum energy required to remove an electron from the metal. The work function of cesium is approximately 1.93 eV.
Converting the work function to joules:
1 eV = 1.602 × 10-19 J
1.93 eV = 1.93 × (1.602 × 10-19) J = 3.08786 × 10-19 J
Now we can calculate the kinetic energy:
KE = (1.2594 × 10⁻¹⁸ J) - (3.08786 × 10⁻¹⁹J) = 9.50712 × 10⁻¹ J
Therefore, the kinetic energy of the emitted electrons when cesium is exposed to UV rays of frequency 1.9 × 10¹⁵ Hz is approximately 9.51 × 10⁻¹⁹ J.
If an atom has 8 valence electrons, how many electrons does it need to gain to achieve a stable electron configuration?
Select all that apply. Greenhouse gases _____. absorb solar energy absorb carbon dioxide release carbon dioxide are released during the combustion of fossil fuels
Gases that trap heat in atmosphere are called Greenhouse gases (GHGs). Examples are carbon dioxide, water vapour, nitrous oxides etc.
The selected choices are that Greenhouse gases-
1. absorb solar energy
2. are released during combustion of fossil fuels.
Which of the following always increases as a system becomes less organized? A. Entropy B. Heat C. Energy D. Temperature
Entropy, the measure of randomness or disorder in a system, increases when a system becomes less organized, such as when ice melts into water.
When a system becomes less organized, the measure of randomness or disorder that increases is known as entropy.
Entropy is a concept in thermodynamics representing the degree of disorder within a system. As energy disperses and becomes more random, entropy increases. This increase in entropy follows the second law of thermodynamics, which states that entropy of any isolated system not in equilibrium almost always increases; it can be thought of as a natural tendency for systems to move towards disorder and spread out energy. For instance, when ice melts into water, entropy increases because the ordered solid structure gives way to a more disordered liquid state, which requires energy input to maintain.
Which statements are correct? Check all that apply. A. An insulator slows the flow of heat. B. A conductor increases the flow of heat. C. A conductor decreases the flow of heat. D. An insulator speeds up the flow of heat.
Which statements are correct? Check all that apply.
A compass is used to make circles and arcs in geometric constructions.
A rough sketch by hand is considered a geometric construction.
Geometric constructions are created with a compass and straightedge.
Protractors are used in geometric constructions to measure degree measures.
Rulers are used in geometric constructions to measure segment lengths.
the answer is 1&3
How do you know that forces are balanced when static friction acts on an object?
Static friction ensures forces are balanced when an object is at rest by matching the applied force up to its limit. This balance means that the net external force on the object is zero. Such conditions imply static equilibrium.
When an object is at rest and static friction is acting on it, the forces are said to be balanced. This state of balance or equilibrium exists because the net external force on the object is zero. According to Newton's first law, an object will remain at rest if no unbalanced force acts on it.
To break it down step-by-step:
The object remains at rest, indicating that all forces acting on it are balanced.The static friction force adjusts to exactly match the applied force, up to its maximum limit, preventing motion.This balance implies that the sum of all forces in any direction is zero.For example, consider a heavy crate on the ground. When you apply a small force to push it, if the crate does not move, the force of static friction equals the applied force but in the opposite direction. This indicates static equilibrium where forces are balanced.
To further understand, let's note that static friction does no work because the point of contact does not move relative to the surface. This characteristic helps in identifying balance as no work is done when forces are perfectly equal and opposite.
hi please help with this question! Need the workings.
A copper penny has a mass of 2.6 g Assuming it is pure copper, how much of this mass is contributed by a) the neutrons in the copper nuclei b) the electrons.
The answers are
a) 1.41 g
b) 6.5 x 10^-4,
The Clean Air Act of 1963 was an improvement over the Air Pollution Control Act of 1955 because it _____.
When a wave strikes a solid barrier it behaves like a basketball hitting a backboard this wave behavior years called?
Why is a small crescent of light often observed on the moon when it is exactly in the new phase?
According to the law of conservation of energy, energy cannot be _____.
A. changed or destroyed
B. created and destroyed
C. created or destroyed
D. created and changed
Answer: B ; created and destroyed
Explanation:
According to the law of conservation of energy, energy can neither be created nor destroyed but can be converted from one form to another
Which simply means you can't create energy and at the same time you can't destroy it.
An energy can be converted from one form to another that is from potential energy to kinetic energy
There is no destruction of energy in such a process
The Law of Conservation of Energy states that energy cannot be created or destroyed. This means that the total amount of energy in a system remains constant. When energy appears to disappear, it has typically been converted to another form.
Explanation:According to the Law of Conservation of Energy, energy cannot be created or destroyed. This is a fundamental law in physics that states that the total amount of energy in an isolated system remains constant over time. For example, when a ball drops from a height, its potential energy is transformed into kinetic energy as it falls, but the total energy within the system (the ball and the Earth) doesn't change. Therefore, the correct answer is C: created or destroyed.
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Identify the following as a suspension or a colloid. sand in water
Johnny was playing baseball with his friends and they noticed a bolt of lightning. They heard thunder seven seconds later. How far away is the storm?
To estimate the distance to a lightning strike, divide the number of seconds between seeing lightning and hearing thunder by five. With a 7-second delay, the storm is approximately 1.4 miles away.
The storm that Johnny and his friends experienced is associated with lightning and thunder. Light from lightning travels much faster than sound from thunder. This difference can be used to estimate the distance to a lightning strike. Since light travels at 3 × 108 meters per second, we see the lightning almost immediately. However, sound travels much slower, and for every 5 seconds we count after seeing lightning before hearing thunder, the storm is approximately 1 mile away.
In Johnny's case, they heard thunder 7 seconds after seeing lightning. Using the rule of thumb that every 5 seconds corresponds to about 1 mile, we can estimate the distance to the storm. 7 seconds divided by 5 gives us 1.4, so the storm is about 1.4 miles away from Johnny and his friends. This is a practical application of basic physics and the differences between light and sound velocity.
When the moon is directly opposite the sun in the sky, its phase is?
What is the magnetic force on a proton that is moving at 2.5 107 m/s to the left through a magnetic field that is 3.4 T and pointing toward you? The charge on a proton is 1.6 10-19 C. Use F = qv B sin(). **I know it's between C or D**
A. 4.0 10-12 N left
B. 4.0 10-12 N right
C. 1.4 10-11 N up
D. 1.4 10-11 N down,
Answer: C. 1.4 10-11 N up
Explanation:
The magnetic force, F on a charge q moving with velocity v in a magnetic field B at an angle θ is given by:
F = q v B sin θ
Charge of proton, q = 1.6 × 10⁻¹⁹ C
Strength of magnetic field, B = 3.4 T pointing outwards
velocity of the proton, v = 2.5 × 10⁷ m/s towards left
Magnetic force is given by:
F = 1.6 × 10⁻¹⁹ C× 2.5 × 10⁷ m/s ×3.4 T× sin 90 = 13.6 × 10⁻¹² N = 1.4 × 10⁻¹¹ N up
The direction of the force is given by Lorentz Right hand rule. The fingers point magnetic field, the thumb points towards velocity, then the force on the proton is given by the direction perpendicular to the palm.
The magnetic field acts outwards with velocity of the proton towards left. The force would act perpendicular to the two -upwards.
The magnetic force on the proton is 1.4 \( \times \) 10-11 N upward, calculated using the formula F = qvB and the right-hand rule for the direction.
Explanation:The magnetic force on a proton moving through a magnetic field can be calculated using the formula F = qvB sin(\theta), where F is the force on the particle, q is the charge of the particle, v is the velocity of the particle, B is the magnetic field, and \theta is the angle between the velocity vector and the magnetic field vector.
Given:
Velocity of the proton, v = 2.5 \( \times \) 107 m/sMagnetic field strength, B = 3.4 TCharge of the proton, q = 1.6 \( \times \) 10-19 CAngle between velocity and magnetic field, \theta = 90 degrees (since the magnetic field is pointing toward you and the proton is moving to the left)For \theta = 90 degrees, sin(\theta) = 1, thus,
F = qvB sin(\theta) = qvB
F = (1.6 \( \times \) 10-19 C) \( \times \) (2.5 \( \times \) 107 m/s) \( \times \) (3.4 T)
F = 1.36 \( \times \) 10-11 N
Using the right-hand rule to determine the direction, the thumb points in the direction of the force. In this case, the force will be directed upward if the magnetic field is into the page and velocity to the left.
Therefore, the correct answer is C. 1.4 \( \times \) 10-11 N up.
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what is the net electrical charge on a magnesium ion that is formed when a neutral atom loses two electrons?
the two main currents that affect the united states on the eat coast and west coast
Answer: The California Current and the Gulf Stream.
Explanation:The Gulf Stream is on the East coast it runs southward to northward While The California Current which is also a part of the North Pacific Gyre moves southward along the westward coast if America and ends off at the southward Baja California peninsula.
The California Current is a Pacific Ocean current.
Other Currents in America are Humboldt Current, the Canary Current, the Benguela Current, and the Somali Current.
Which of the following occurs in January when the earth is closest to the sun?
Final answer:
The correct option is A Perihelion. Perihelion is the event that occurs in January when the Earth is closest to the Sun, and it results in the Earth being approximately 91.5 million miles from the Sun.
Explanation:
The event that occurs in January when the Earth is closest to the Sun is called perihelion. This is the point in Earth's elliptical orbit where it is at the minimum possible distance from the Sun. The Earth reaches perihelion approximately around January 3rd, depending on the year, with a slight variation over time.
At perihelion, the Earth is about 91.5 million miles from the Sun, as opposed to during aphelion, the farthest point, when it is about 94 million miles away. During this time, despite the Earth receiving more heat from the Sun, the Northern Hemisphere experiences winter because of the axial tilt directing this hemisphere away from the Sun.
Over long periods, the dates of perihelion and aphelion gradually shift due to the precession of the Earth's orbit. This change can have significant climatic effects over geological timescales.
Which platform did Mr. Ray’s marketing team advise him to use for the launch of a new product?
Mr. Ray is looking for a platform to launch his product. His marketing team advises him to launch the product via_____ as it is free advertising and improves_____.
1. A. Newspapers A. Product Quality
B.social Media B. Consumer Welfare
C.Billboards C. Brand Reconition
Social Media and Brand Recognition
You hear the engine roaring on a race car at the starting line. Predict the changes in the sound as the race starts and the car approaches the camera. A) The sound of the engine will get louder and the pitch lower. Eliminate B) The sound of the engine will get louder and the pitch higher. C) The sound is determined by the car and it will not change in any way. D) The sound of the engine will get louder but the pitch will not change.
B. The sound of the engine will get louder and the pitch higher.
Answer: The correct option is B.
Explanation:
Doppler effect is the phenomenon in which there is an apparent change in the frequency when there is relative motion between source and listener.
When the source and the listener are approaching each other then the frequency increases. The loudness depends on the amplitude. The energy of the wave is directly proportional to the square of the amplitude.
In the given problem, the engine is roaring on a race car at the starting line. There is change in the sound as the race starts and the car approaches the camera.
Pitch depends on the frequency.
Therefore, the sound of the wave will get louder and the pitch will get higher.
Which of the following is not a name of a scale for measuring temperature? A. Kelvin B. Celsius C. Absolute D. Fahrenheit
Answer:
Kelvin, Celsius, and Fahrenheit
Explanation:
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Car A has a mass of 1,200 kg and is traveling at a rate of 22 km/hr. It collides with car B. Car B has a mass of 1,900 kg and is traveling in the same direction at 25 km/hr. Which of the following statements is true?
The momentum before the collision is equal to the momentum after the collision.
The momentum before the collision is greater than the momentum after the collision.
The momentum before the collision is less than the momentum after the collision.,
Match the type of boundary with its characteristic
The required relation is given in the figure below
ExplanationThere are three main types of plate boundaries:
Convergent boundaries: where two plates are colliding.Divergent boundaries – where two plates are moving apart. ... Transform boundaries – where plates slide passed each otherWhich best explains what happens to the motion of the pendulum?
A.The mechanical energy transforms to thermal energy as the pendulum slows and eventually stops moving.
B.The mechanical energy disappears as the pendulum slows and eventually stops moving.
C.The pendulum will continue moving at the same speed until someone stops it because energy cannot be destroyed.
D.The pendulum will slow down but will never stop moving because energy cannot be destroyed.
Holding a book while walking means i am doing work on the book. true or false
How much does it cost to operate a 25-w soldering iron for 8.0 hours if energy costs 8.0¢/kwh?
To find the cost of operating a 25-watt soldering iron for 8 hours at an energy cost of 8.0 cents per kWh, first convert the iron's wattage to kilowatts, then multiply by the hours to get kWh, and finally multiply by the cost per kWh. The total cost comes to 1.6 cents.
Explanation:To calculate the cost of operating a 25-watt soldering iron for 8.0 hours with electricity costing 8.0 cents per kilowatt-hour, we first need to convert the power usage into kilowatts and then multiply by the number of hours used to find the total energy consumed in kilowatt-hours (kWh). Finally, we multiply the energy consumed by the cost per kWh to find the total cost.
First, we convert watts to kilowatts:
25 watts = 0.025 kilowatts (kW).
Next, we multiply the power consumption by the number of hours used:
0.025 kW × 8.0 hours = 0.2 kWh.
Lastly, we calculate the total cost:
0.2 kWh × $0.08 per kWh = $0.016.
So, operating a 25-watt soldering iron for 8 hours would cost 1.6 cents.
. The penalties for a person's second DUI conviction include completion of __________ hours of DUI school.
A 10-kilogram bicycle is traveling at a speed of 2m/s. what is the bike's kinetice energy?
A hydraulic jack is used to lift a car in order to change a tire. The car exerts a force of 9,800 N toward the ground due to the force of gravity.
1. To begin to lift the car, a hydraulic jack must produce ______ of force.
A. more than 9,800 N
B. less than 9,800 N
C. exactly 9,800 N
2. To keep the car in position once it is lifted, the jack must produce _____ of force.
A. more than 9,800 N
B. less than 9,800 N
C. exactly 9,800 N
Force is defined as the product of mass and acceleration or gravity. Force is calculated in Newton.
The force required to lift the car should be more than 9,800 N, and, to keep the car in position, the force should be exactly same as 9,800 N.
The force is a vector quantity, calculated as the product of mass and acceleration (sometimes gravity.) In order to lift the car, Jack must apply a force greater than the weight of the car.
As given in the question, the weight of the object is 9,800 N. The weight is equal to the force when the object is at rest.
Also, once the car is lifted, Jack must maintain the force exactly 9,800 N. The less force of the car will cause the gravity to pull the car downwards.
Therefore, the force should be exactly 9,800 N while lifting and should be more than 9,800 N, when beginning to lift the car.
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A ramp is 1.0 m high and 3.0 m long. What is the IMA of the ramp?
Final answer:
The Ideal Mechanical Advantage (IMA) of a ramp that is 1.0 m high and 3.0 m long is 3, indicating that the ramp multiplies the input force by a factor of 3.
Explanation:
The IMA (Ideal Mechanical Advantage) of a ramp is determined by the ratio of the distance along the ramp's slope (the length of the incline) to the vertical height of the ramp. To calculate the IMA of this particular ramp, which is 1.0 m high and 3.0 m long, you would divide the length by the height:
IMA = Length of the incline / Height = 3.0 m / 1.0 m = 3.
The Ideal Mechanical Advantage of the ramp is 3. This indicates that the ramp multiplies the input force by a factor of 3, meaning for every 1 unit of force applied along the ramp, the output force that lifts the object is 3 units.