Speed of electromagnetic waves is the same:
- For all wavelengths.
- In all media.
- For all intensities.
- For all frequencies.
Question types
Electromagnetic Waves question types
30 questions across 5 question groups — pick any mix to generate a Physics paper with step-by-step answer keys.
30
Questions
5
Question groups
5
Question types
01
M.C.Q (1 Marks)
14 Q→022 Marks Questions
1 Q→033 Marks Question
11 Q→044 Marks Question
2 Q→055 Marks Questions
2 Q→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.
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Which of the following have zero average value in a plane electromagnetic wave?
- Electric field.
- Magnetic field.
- Electric energy.
- Magnetic energy.
Displacement current goes through the gap between the plates of a capacitor when the charge of the capacitor:
- Increases.
- Decreases.
- Does not change.
- Is zero.
Consider the following two statements regarding a linearly polarised, plane electromagnetic wave:
- The electric field and the magnetic field have equal average values.
- The electric energy and the magnetic energy have equal average values.
- Both A and B are true.
- A is false but B is true.
- B is false but A is true
- Both A and B are false.
A compass needle is placed in the gap of a parallel plate capacitor. The capacitor is connected to a battery through a resistance. The compass needle:
- Does not deflect.
- Deflects for a very short time and then comes back to the original position.
- Deflects and remains deflected as long as the battery is connected.
- Deflects and gradually comes to the original position in a time that is large compared to the time constant.
Show that the dimensions of the displacement current $\in_0\frac{\text{d}\phi_\text{E}}{\text{dt}}$ are that of an electric current.
View full solution →The magnetic field in a plane electromagnetic wave is given by $\text{B}=(200\mu\text{T})\sin\Big[\big(4.0\times10^{15}\text{s}^{-1}\big)\Big(\text{t}-\frac{\text{x}}{\text{c}}\Big)\Big]$ Find the maximum electric field and the average energy density corresponding to the electric field.
View full solution →Using $\text{B}=\mu_0\text{H},$ find the ratio $\frac{\text{E}_0}{\text{H}_0}$ for a plane electromagnetic wave propagating through vacuum. Show that it has the dimensions of electric resistance. This ratio is a universal constant called the impedance of free space.
View full solution →A point charge is moving along a straight line with a constant velocity u. Consider a small area A perpendicular to the direction of motion of the charge (El). Calculate the displacement current through the area when its distance from the charge is x. The value of x is not large so that the electric field at any instant is essentially given by Coulomb's law.
A laser beam has intensity 2.5 × 1014Wm-2. Find amplitudes of electric and magnetic fields in the beam.
A parallel-plate capacitor of plate-area A and plate separation d is joined to a battery of emf $\in$ and internal resistance R at t = 0. Consider a plane surface of area $\frac{\text{A}}{2}$ parallel to the plates and situated symmetrically between them. Find the displacement current through this surface as a function of time.
View full solution →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.
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.
The intensity of the sunlight reaching Earth is 1380Wm-2. Assume this light to be a plane, monochromatic wave. Find the amplitudes of electric and magnetic fields in this wave.
A plane electromagnetic wave is passing through a region. Consider (a) electric field (b) magnetic field (c) electrical energy in a small volume and (d) magnetic energy in a small volume. Construct the pairs of the quantities that oscillate with equal frequencies.
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