Question 1

Light with an intensity of 1 kW/m2 falls normally on a surface with an area of 1 cm2 and is completely reflected. The force of the radiation on the surface is:

Accepted Answer

A)  1.0 * 10-4 N 
B)  3.3 * 10-11 N 
C)  1.7 * 10-10 N 
D)  3.3 *10-10 N 
E)  6.7 *10-10 N 
A)  1.0 * 10-4 N 
B)  3.3 * 10-11 N 
C)  1.7 * 10-10 N 
D)  3.3 *10-10 N 
E)  6.7 *10-10 N E

Question 2

The units of index of refraction are:

Accepted Answer

A)  m/s 
B)  s/m 
C)  radian 
D)  m/s2 
E)  none of these 
A)  m/s 
B)  s/m 
C)  radian 
D)  m/s2 
E)  none of these E

Question 3

Of the following human eyes are most sensitive to:

Accepted Answer

A)  red light 
B)  violet light 
C)  blue light 
D)  green light 
E)  none of these (they are equally sensitive to all colors) 
A)  red light 
B)  violet light 
C)  blue light 
D)  green light 
E)  none of these (they are equally sensitive to all colors) D

Question 4

The light intensity 10 m from a point source is 1000 W/m2. The intensity 100 m from the same source is:

Accepted Answer

A)  1000 W/m2 
B)  100 W/m2 
C)  10 W/m2 
D)  1 W/m2 
E)  0.1 W/m2 
A)  1000 W/m2 
B)  100 W/m2 
C)  10 W/m2 
D)  1 W/m2 
E)  0.1 W/m2

Question 5

Radio waves of wavelength 300 m have a frequency of:

Accepted Answer

A)  10-6 kHz 
B)  500 kHz 
C)  1 MHz 
D)  9 MHz 
E)  108 kHz 
A)  10-6 kHz 
B)  500 kHz 
C)  1 MHz 
D)  9 MHz 
E)  108 kHz

Question 6

Which diagram below illustrates the path of a light ray as it travels from a given point X in air to another given point Y in glass?

Accepted Answer

A)  I 
B)  II 
C)  III 
D)  IV 
E)  V 
A)  I 
B)  II 
C)  III 
D)  IV 
E)  V

Question 7

Select the correct statement:

Accepted Answer

A)  ultraviolet light has a longer wavelength than infrared 
B)  blue light has a higher frequency than x rays 
C)  radio waves have higher frequency than gamma rays 
D)  gamma rays have higher frequency than infra-red waves 
E)  electrons are a type of electromagnetic wave 
A)  ultraviolet light has a longer wavelength than infrared 
B)  blue light has a higher frequency than x rays 
C)  radio waves have higher frequency than gamma rays 
D)  gamma rays have higher frequency than infra-red waves 
E)  electrons are a type of electromagnetic wave

Question 8

Light of uniform intensity shines perpendicularly on a totally absorbing surface, fully illuminating the surface. If the area of the surface is decreased:

Accepted Answer

A)  the radiation pressure increases and the radiation force increases 
B)  the radiation pressure increases and the radiation force decreases 
C)  the radiation pressure stays the same and the radiation force increases 
D)  the radiation pressure stays the same and the radiation force decreases 
E)  the radiation preassure decreases and the radiation force decreases 
A)  the radiation pressure increases and the radiation force increases 
B)  the radiation pressure increases and the radiation force decreases 
C)  the radiation pressure stays the same and the radiation force increases 
D)  the radiation pressure stays the same and the radiation force decreases 
E)  the radiation preassure decreases and the radiation force decreases

Question 9

For an electromagnetic wave the direction of the vector   gives:

Accepted Answer

A)  the direction of the electric field 
B)  the direction of the magnetic field 
C)  the direction of wave propagation 
D)  the direction of the electromagnetic force on a proton 
E)  the direction of the emf induced by the wave 
A)  the direction of the electric field 
B)  the direction of the magnetic field 
C)  the direction of wave propagation 
D)  the direction of the electromagnetic force on a proton 
E)  the direction of the emf induced by the wave

Question 10

Visible light has a frequency of about:

Accepted Answer

A)  5 * 1018 Hz 
B)  5 * 1016 Hz 
C)  5 *1014 Hz 
D)  5 *1012 Hz 
E)  5 * 1010 Hz 
A)  5 * 1018 Hz 
B)  5 * 1016 Hz 
C)  5 *1014 Hz 
D)  5 *1012 Hz 
E)  5 * 1010 Hz

Question 11

A point source emits electromagnetic energy at a rate of 100 W. The intensity 10 m from the source is:

Accepted Answer

A)  10 W/m2 
B)  1.6 W/m2 
C)  1 W/m2 
D)  0.024W/m2 
E)  0.080 W/m2 
A)  10 W/m2 
B)  1.6 W/m2 
C)  1 W/m2 
D)  0.024W/m2 
E)  0.080 W/m2

Question 12

When light travels from medium X to medium Y as shown:

Accepted Answer

A)  both the speed and the frequency decrease 
B)  both the speed and the frequency increase 
C)  both the speed and the wavelength decrease 
D)  both the speed and the wavelength increase 
E)  both the wavelength and the frequency are unchanged 
A)  both the speed and the frequency decrease 
B)  both the speed and the frequency increase 
C)  both the speed and the wavelength decrease 
D)  both the speed and the wavelength increase 
E)  both the wavelength and the frequency are unchanged

Question 13

A pole stands in a river, half in and half out of the water. Another pole of the same length stands vertically on the shore at a place where the ground is level. The shadow cast by the pole in the river on the river bottom is:

Accepted Answer

A)  slightly longer than the shadow of the pole on land 
B)  much longer than the shadow of the pole on land 
C)  shorter than the shadow of the pole on land 
D)  shorter than the shadow of the pole on land if the sun is high and longer if the sun is low 
E)  the same length as the shadow of the pole on land 
A)  slightly longer than the shadow of the pole on land 
B)  much longer than the shadow of the pole on land 
C)  shorter than the shadow of the pole on land 
D)  shorter than the shadow of the pole on land if the sun is high and longer if the sun is low 
E)  the same length as the shadow of the pole on land

Question 14

Radio waves of wavelength 3 cm have a frequency of:

Accepted Answer

A)  1 MHz 
B)  9 MHz 
C)  100 MHz 
D)  10,000 MHz 
E)  900 MHz 
A)  1 MHz 
B)  9 MHz 
C)  100 MHz 
D)  10,000 MHz 
E)  900 MHz

Question 15

The magnetic field in a sinusoidal light wave has an amplitude of 3.3 *10-7 T. The intensity of the wave is:

Accepted Answer

A)  1.7* 10-4 W/m2 
B)  13 W/m2 
C)  27 W/m2 
D)  1.0 * 105 W/m2 
E)  4.0 *1010 W/m2 
A)  1.7* 10-4 W/m2 
B)  13 W/m2 
C)  27 W/m2 
D)  1.0 * 105 W/m2 
E)  4.0 *1010 W/m2

Question 16

A plane electronmagnetic wave is travelling in the positive x direction. At the instant shown the electric field at the extremely narrow dashed rectangle is in the negative z direction and its magnitude is decreasing. Which diagram correctly shows the directions and relative magnitudes of the electric field at the edges of the rectangle?

Accepted Answer

A)  A 
B)  B 
C)  C 
D)  D 
E)  E 
A)  A 
B)  B 
C)  C 
D)  D 
E)  E

Question 17

Maxwell's equations predict that the speed of electromagnetic waves in free space is given by:

Accepted Answer

A)    
B)    
C)    
D)    
E)    
A)    
B)    
C)    
D)    
E)

Question 18

The time averaged energy in a sinusoidal electromagnetic wave is:

Accepted Answer

A)  overwhelmingly electrical 
B)  slightly more electrical than magnetic 
C)  equally divided between the electric and magnetic fields 
D)  slightly more magnetic than electrical 
E)  overwhelmingly magnetic 
A)  overwhelmingly electrical 
B)  slightly more electrical than magnetic 
C)  equally divided between the electric and magnetic fields 
D)  slightly more magnetic than electrical 
E)  overwhelmingly magnetic

Question 19

Light with an intensity of 1 kW/m2 falls normally on a surface and is completely absorbed. The radiation pressure is:

Accepted Answer

A)  1 kPa 
B)  3 * 1011 Pa 
C)  1.7 * 10-6 Pa 
D)  3.3 *10-6 Pa 
E)  6.7 * 10-6 Pa 
A)  1 kPa 
B)  3 * 1011 Pa 
C)  1.7 * 10-6 Pa 
D)  3.3 *10-6 Pa 
E)  6.7 * 10-6 Pa

Question 20

Which of the following is NOT true for electromagnetic waves?

Accepted Answer

A)  they consist of changing electric and magnetic fields 
B)  they travel at different speeds in vacuum, depending on their frequency 
C)  they transport energy 
D)  they transport momentum 
E)  they can be reflected 
A)  they consist of changing electric and magnetic fields 
B)  they travel at different speeds in vacuum, depending on their frequency 
C)  they transport energy 
D)  they transport momentum 
E)  they can be reflected

Exam 33: Electromagnetic Waves

Light with an intensity of 1 kW/m2 falls normally on a surface with an area of 1 cm2 and is completely reflected. The force of the radiation on the surface is:

The units of index of refraction are:

Of the following human eyes are most sensitive to:

The light intensity 10 m from a point source is 1000 W/m2. The intensity 100 m from the same source is:

Radio waves of wavelength 300 m have a frequency of:

Which diagram below illustrates the path of a light ray as it travels from a given point X in air to another given point Y in glass?

Select the correct statement:

Light of uniform intensity shines perpendicularly on a totally absorbing surface, fully illuminating the surface. If the area of the surface is decreased:

For an electromagnetic wave the direction of the vector gives:

Visible light has a frequency of about:

A point source emits electromagnetic energy at a rate of 100 W. The intensity 10 m from the source is:

When light travels from medium X to medium Y as shown:

A pole stands in a river, half in and half out of the water. Another pole of the same length stands vertically on the shore at a place where the ground is level. The shadow cast by the pole in the river on the river bottom is:

Radio waves of wavelength 3 cm have a frequency of:

The magnetic field in a sinusoidal light wave has an amplitude of 3.3 *10-7 T. The intensity of the wave is:

Maxwell's equations predict that the speed of electromagnetic waves in free space is given by:

The time averaged energy in a sinusoidal electromagnetic wave is:

Light with an intensity of 1 kW/m2 falls normally on a surface and is completely absorbed. The radiation pressure is:

Which of the following is NOT true for electromagnetic waves?

Measurement

Motion Along a Straight Line

Vector

Motion in Two and Three Dimensions

Force and Motion I

Force and Motion II

Kinetic Energy and Work

Potential Energy and Conservation of Energy

Center of Mass and Linear Momentum

Rotation

Rolling, Torque, and Angular Momentum

Equilibrium and Elasticity

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The Kinetic Theory of Gases

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Magnetic Fields Due to Currents

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Electromagnetic Oscillations and Alternating Current

Maxwells Equations; Magnetism of Matter

Images

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Energy From the Nucleus

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Filters

Light with an intensity of 1 kW/m² falls normally on a surface with an area of 1 cm² and is completely reflected. The force of the radiation on the surface is:

The light intensity 10 m from a point source is 1000 W/m². The intensity 100 m from the same source is:

The magnetic field in a sinusoidal light wave has an amplitude of 3.3 *10^-⁷T. The intensity of the wave is:

Light with an intensity of 1 kW/m² falls normally on a surface and is completely absorbed. The radiation pressure is: