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Electromagnetic Waves Physics - Electromagnetic Waves

Rajasthan Board (RBSE) - STD 12 Science - Physics (Rajasthan - English Medium). 337 questions in this chapter.

Question types

Electromagnetic Waves question types

337 questions across 7 question groups — pick any mix to generate a Physics paper with step-by-step answer keys.

337
Questions
7
Question groups
5
Question types
Sample Questions

Electromagnetic Waves questions

One sample from each question group in this chapter. Select any group above to see the full set with answer keys.

Q 1M.C.Q (1 Marks)1 Mark
An electric field $\overrightarrow{\text{E}}$ and a magnetic field $\overrightarrow{\text{B}}$ exist in a region. The fields are not perpendicular to each other.
  • A
    This is not possible.
  • B
    No electromagnetic wave is passing through the region.
  • ✓
    An electromagnetic wave may be passing through the region.
  • D
    An electromagnetic wave is certainly passing through the region.

Answer: C.

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Q 3M.C.Q (1 Marks)1 Mark
Monica wanted to take photographs of a monument. But since the surrounding is filled with smoke, she is not able to take good photos. Which one of the following electromagnetic waves can be used in this situation to help Monica?
  • A
    $X-$rays
  • B
    Gamma rays
  • C
    Ultraviolet rays
  • ✓
    Infrared waves

Answer: D.

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Q 5M.C.Q (1 Marks)1 Mark
Which of the following electromagnetic waves is used in medicine to destroy cancer cells?
  • A
    $IR-$rays
  • B
    Visible rays
  • ✓
    Gamma rays
  • D
    Ultraviolet rays

Answer: C.

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Q 6Assertion (A) & Reason (B) MCQ1 Mark
Two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
  1. Both A and R are true and R is the correct explanation of A.
  2. Both A and R are true but R is not the correct explanation of A.
  3. A is true but R is false.
  4. A is false and R is also false.
Assertion: X-rays in vacuum travel faster than light waves in vacuum
Reason: The energy of X-rays photon is less than that of light photon.
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Q 7Assertion (A) & Reason (B) MCQ1 Mark
Two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
  1. Both A and R are true and R is the correct explanation of A.
  2. Both A and R are true but R is not the correct explanation of A.
  3. A is true but R is false.
  4. A is false and R is also false.
Assertion: Electromagnetic waves exert pressure called radiation pressure.
Reason: Electromagnetic waves carries energy.
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Q 8Assertion (A) & Reason (B) MCQ1 Mark
Two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
  1. Both A and R are true and R is the correct explanation of A.
  2. Both A and R are true but R is not the correct explanation of A.
  3. A is true but R is false.
  4. A is false and R is also false.
Assertion: The microwaves are better carriers of signals than radio wave.
Reason: The electromagnetic waves do not required any material medium for propagation.
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Q 9Assertion (A) & Reason (B) MCQ1 Mark
Two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
  1. Both A and R are true and R is the correct explanation of A.
  2. Both A and R are true but R is not the correct explanation of A.
  3. A is true but R is false.
  4. A is false and R is also false.
Assertion: In an electromagnetic wave, magnitude of magnetic field vector is much smaller than the magnitude of electric field vector.
Reason: Energy of electromagnetic waves is shared equally by the electric and magnetic fields.
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Q 10Assertion (A) & Reason (B) MCQ1 Mark
Two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
  1. Both A and R are true and R is the correct explanation of A.
  2. Both A and R are true but R is not the correct explanation of A.
  3. A is true but R is false.
  4. A is false and R is also false.
Assertion: Infrared waves sometimes referred as heat waves.
Reason: Infrared waves heat up the earth surface.
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Q 111 Marks Question1 Mark
Suppose that the electric field part of an electromagnetic wave in vacuum is $\text{E}=\{(3.1 \ \text{N}/\text{C}\cos[(1.8 \text{rad}/ \text{m}) \text{y}+(5.4\times10^6 \ \text{red}/\text{s}\text{t}]\hat{\text{i}}\}$.
  1. What is the direction of propagation?
  2. What is the wavelength λ ?
  3. What is the frequency ν ?
  4. What is the amplitude of the magnetic field part of the wave?
  5. Write an expression for the magnetic field part of the wave.
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Q 121 Marks Question1 Mark
shows a capacitor made of two circular plates each of radius 12 cm, and separated by 5.0 cm. The capacitor is being charged by an external source (not shown in the figure). The charging current is constant and equal to 0.15A.
  1. Calculate the capacitance and the rate of charge of potential difference between the plates.
  2. Obtain the displacement current across the plates.
  3. Is Kirchhoff’s first rule (junction rule) valid at each plate of the capacitor? Explain.
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Q 162 Marks Questions2 Marks
Identify the electromagnetic waves whose wavelengths lie in the range:
  1. $10^{-11} \mathrm{~m}<\lambda<10^{-14} \mathrm{~m}$
  2. $10^{-4} \mathrm{~m}<\lambda<10^{-6} \mathrm{~m}$
Write one use for each.
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Q 172 Marks Questions2 Marks
Identify the electromagnetic waves whose wavelengths vary as
  1. $10^{-12 \mathrm{~m}}<\lambda<10^{-8} \mathrm{~m}$
  2. $10^{-3 \mathrm{~m}}<\lambda<10^{-1} \mathrm{~m}$
Write one use for each.
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Q 182 Marks Questions2 Marks
Draw a sketch of a plane electromagnetic wave propagating along the z-direction. Depict clearly the directions of electric and magnetic fields varying sinusoidally with z.
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Q 192 Marks Questions2 Marks
How does Ampere-Maxwell law explain the flow of current through a capacitor when it is being charged by a battery? Write the expression for the displacement current in terms of the rate of change of electric flux.
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Q 202 Marks Questions2 Marks
  1. An em wave is travelling in a medium with a velocity $\overrightarrow{\text{v}} = \text{v}\hat{\text{i}}.$ Draw a sketch showing the propagation of the em wave, indicating the direction of the oscillating electric and magnetic fields.
  2. How are the magnitudes of the electric and magnetic fields related to the velocity of the em wave?
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Q 213 Marks Question3 Marks
What physical quantity is the same for X - rays of wavelength $10^{-10}\ m$, red light of wavelength 6800 Å and radiowaves of wavelength 500m?
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Q 223 Marks Question3 Marks
Use the formula $\lambda _m\ T = 0.29\ cm\ K$ to obtain the characteristic temperature ranges for different parts of the electromagnetic spectrum. What do the numbers that you obtain tell you?
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Q 233 Marks Question3 Marks
How are electromagnetic waves produced? What is the source of energy carried by a propagating electromagnetic wave? Identify the electromagnetic radiations used:
  1. In remote switches of household electronic devices.
  2. As diagnostic tool in medicine.
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Q 243 Marks Question3 Marks
  1. Identify the part of the electromagnetic spectrum which is:
  1. Suitable for radar system used in aircraft navigation,
  2. Produced by bombarding a metal target by high-speed electrons.
  1. Why does a galvanometer show a momentary deflection at the time of charging or discharging a capacitor? Write the necessary expression to explain this observation.
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Q 253 Marks Question3 Marks
Identify the following electromagnetic radiations as per the wavelengths given below.
Write one application of each.
  1. $10^{–3}nm$
  2. $10^{–3} m$
  3. $1 nm$
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Q 265 Marks Questions5 Marks
Answer the following question:
Some scientists have predicted that a global nuclear war on the earth would be followed by a severe ‘nuclear winter’ with a devastating effect on life on earth. What might be the basis of this prediction?
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Q 275 Marks Questions5 Marks
In a plane electromagnetic wave, the electric field oscillates sinusoidally at a frequency of $2.0 \times 10^{10} $Hz and amplitude $48\ V\ m^{-1}.$
  1. What is the wavelength of the wave?
  2. What is the amplitude of the oscillating magnetic field?
  3. Show that the average energy density of the E field equals the average energy density of the B field. $[c = 3 \times 10^8\ m\ s^{-1}.]$
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Q 285 Marks Questions5 Marks
The terminology of different parts of the electromagnetic spectrum is given in the text. Use the formula E = hν (for energy of a quantum of radiation: photon) and obtain the photon energy in units of eV for different parts of the electromagnetic spectrum. In what way are the different scales of photon energies that you obtain related to the sources of electromagnetic radiation?
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Q 295 Marks Questions5 Marks
Answer the following question:
If the earth did not have an atmosphere, would its average surface temperature be higher or lower than what it is now?
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Q 305 Marks Questions5 Marks
Suppose that the electric field amplitude of an electromagnetic wave is $E_0 = 120$ N/C and that its frequency is $ν = 50.0 $ MHz. (a) Determine, $B_0, ω, k$, and \lambda . (b) Find expressions for E and B.
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Q 31Case study (4 Marks)4 Marks
In a microwave oven, the food is kept in a plastic container and the microwave is directed towards the food. The food is cooked without melting or igniting the plastic container. Explain.
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Q 32Case study (4 Marks)4 Marks
A metal rod is placed along the axis of a solenoid carrying a high-freqμency alternating current. It is found that the rod gets heated. Explain why the rod gets heated.
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Q 33Case study (4 Marks)4 Marks
Professor C.V Raman surprised his students by suspending freely a tiny light ball in a transparent vacuum chamber by shining a laser beam on it. Which property of EM waves was he exhibiting? Give one more example of this property.
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Q 34Case study (4 Marks)4 Marks
Electrons oscillating in a circuit give rise to radiowaves. A transmitting antenna radiates most effectively the radiowaves of wavelength equal to the size of the antenna. The infrared waves incident on a substance set into oscillation all its electrons, atoms and molecules. This increases the internal energy and hence the temperature of the substance.
  1. If $v_g, v_x$ and $v_m$ are the speeds of gamma rays, X-rays and microwaves respectively in vacuum, the
  1. $v_g > v_x > v_m$
  2. $v_g < v_x < v_m$
  3. $v_g > v_x > v_m$
  4. $v_g = v_x = v_m$
  1. Which of the following wi II deflect in electric field?
  1. X-rays.
  2. $\gamma-\text{rays}.$
  3. Cathode rays.
  4. Ultraviolet rays.
  1. $\gamma-\text{rays}$ are detected by:
  1. Point contact diodes.
  2. Thennopiles.
  3. Ionization chamber.
  4. Photocells.
  1. The frequency of electromagnetic wave, which best suited to observe a particle ofradius $3 \times 10^{-4}cm$ is the order of,
  1. $10^{15}Hz$
  2. $10^{14} Hz$
  3. $10^{13}Hz$
  4. $10^{12}Hz$
  1. We consider the radiation emitted by the human body. Which one of the following statements is true?
  1. The radiation emitted is in the infrared region.
  2. The radiation is emitted only during the day.
  3. The radiation is emitted during the summers and absorbed during the winters.
  4. The radiation emitted lies in the ultraviolet region and hence it is not visible.
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Q 35Case study (4 Marks)4 Marks
Radio waves are produced by the accelerated motion of charges in conducting wires. Microwaves are produced by special vacuum tubes. Infrared waves are produced by hot bodies and molecules also known as heat waves. UV rays are produced by special lamps and very hot bodies like Sun.
  1. Solar radiation is:
  1. Transverse electromagnetic wave.
  2. Longitudinal electromagnetic waves.
  3. Both longitudinal and transverse electromagnetic waves.
  4. None of these.
  1. What is the cause of greenhouse effect?
  1. Infrared rays.
  2. Ultraviolet rays
  3. X-rays.
  4. Radiowaves.
  1. Biological importance of ozone layer is:
  1. It stops ultraviolet rays.
  2. It layer reduces greenhouse effect.
  3. It reflects radiowaves.
  4. None of these.
  1. Ozone is found in.
  1. Stratosphere.
  2. Ionosphere.
  3. Mesosphere.
  4. Troposphere.
  1. Earth's atmosphere is richest in.
  1. Ultraviolet.
  2. Infrared.
  3. X-rays.
  4. Microwave.
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