Electromagnetic Waves quiz

The speed of electromagnetic waves in vacuum is:

Displacement current arises due to:

Electromagnetic waves are:

X-rays have wavelengths of the order of:

Radar uses:

Ultraviolet radiation from the Sun is largely absorbed by:

Infrared waves are also called:

Gamma rays are emitted from:

In an electromagnetic wave, the electric and magnetic fields are:

Which electromagnetic waves have the longest wavelength?

Why are microwaves used in microwave ovens? (2 marks)

Why is infrared radiation used in remote controls and night vision? (2 marks)

How do electromagnetic waves carry energy and momentum? (2 marks)

Write the relation between E0, B0 and c for an electromagnetic wave. (2 marks)

Why are X-rays used for imaging bones? (2 marks)

Do electromagnetic waves need a medium? Explain. (2 marks)

What is the role of the ozone layer in protecting life? (2 marks)

Name the scientist who first produced and detected electromagnetic waves experimentally. (2 marks)

Why do welders wear special goggles? (2 marks)

Which part of the electromagnetic spectrum is used in optical fibre communication? (2 marks)

Find the wavelength of the waves of an AM radio station broadcasting at 1 MHz. (3 marks)

The electric field amplitude of an electromagnetic wave is 120 N/C. Find the amplitude of the magnetic field. (3 marks)

Find the frequency of X-rays of wavelength 1 nm and the energy of each photon in eV (hc = 1240 eV nm). (3 marks)

A 100 pF capacitor is being charged so that the voltage across it changes at 10^6 V/s. Find the displacement current between its plates. (3 marks)

Light of frequency 5 x 10^14 Hz enters glass of refractive index 1.5. Find its speed and wavelength in glass. (3 marks)

Read the passage and answer the questions. A microwave oven uses waves of frequency 2.45 GHz. Water molecules in food absorb this energy and heat up, but a glass bowl stays cooler. (i) Find the wavelength of these waves. (ii) Why do water molecules absorb microwaves strongly? (iii) Why should metal containers not be used? (5 marks)

Read the passage and answer the questions. Dermatologists advise using sunscreen on sunny days because prolonged exposure to certain solar radiation causes sunburn and may lead to skin cancer. (i) Which radiation causes sunburn? (ii) Give its wavelength range. (iii) Why does ordinary glass reduce sunburn? (5 marks)

Read the passage and answer the questions. Mobile phones communicate with towers using electromagnetic waves of frequency around 900 MHz to 2.5 GHz. (i) Which band of the spectrum is used? (ii) Find the wavelength at 900 MHz. (iii) Why must towers be placed in line of sight in hilly areas? (5 marks)

Read the passage and answer the questions. In a hospital, X-rays are used to image a fractured bone, and gamma rays from cobalt-60 are used to treat cancer. (i) Which has the higher frequency? (ii) How are X-rays produced? (iii) Why must exposure to both be limited? (5 marks)

Read the passage and answer the questions. Sunlight passes through the atmosphere and warms the Earth. The warm Earth emits infrared radiation, part of which is trapped by carbon dioxide and water vapour. (i) Name this effect. (ii) Why does the Earth emit infrared rather than visible light? (iii) How does increased CO2 affect global temperature? (5 marks)

Explain the concept of displacement current and derive the Ampere-Maxwell law, with a diagram of a charging capacitor. (6 marks)

Describe the electromagnetic spectrum with frequency ranges and uses of each part, with a labelled chart. (6 marks)

State the properties of electromagnetic waves and draw a diagram showing the electric and magnetic fields of a plane wave. (6 marks)

Explain how electromagnetic waves are produced by accelerating charges and describe how Hertz detected them. (6 marks)

Write Maxwell's four equations in words, and explain how they predict electromagnetic waves travelling at the speed of light. (6 marks)