Electromagnetic | MCQs

Explanation

Red light rays have the lowest frequency and highest wavelength value.

Blue or violet light has the shortest wavelength.

Explanation

• The wavelength of a transverse wave is the distance between two adjacent crests or troughs.
• It is a fundamental property of waves.
• It is typically denoted by the symbol λ (lambda).

Explanation

A step-up transformer increases the voltage of the input signal, resulting in a higher voltage output.

This is achieved by having more turns in the secondary coil than in the primary coil.

Explanation

Light varies continuously in intensity and wavelength, making it an analog signal.

Analog signals have values that change smoothly over time — just like natural light.

Explanation

Gamma (γ) radiation consists of high-energy electromagnetic waves, such as X-rays or gamma rays, that travel in a straight line and are not affected by electric or magnetic fields.

Gamma radiation is a form of ionizing radiation and can travel several meters in air or several centimeters in dense materials before being absorbed.

Explanation

If the direction of the magnetic field is reversed, the direction of the force exerted on a charged particle or a current-carrying wire will also be reversed.

This is because the force due to a magnetic field depends on the direction of the field.

The direction of the current or velocity, and the charge of the particle (if applicable).

Explanation

Electric fields can be detected by electrons, which are charged particles that respond to the force exerted by the electric field.

Electrons will accelerate or decelerate in the presence of an electric field, allowing for the detection of the field.

Explanation

A turn ratio of 10 means that the secondary coil (Ns) has 10 times more turns than the primary coil (Np).

This is a step-up transformer, which increases the voltage and decreases the current.

Explanation

The direction of induced e.m.f. (electromotive force) in a circuit is determined by Lenz's law.

It states that the induced e.m.f. will oppose the change in magnetic flux that induced it.

This is a consequence of the conservation of energy.

Explanation

When a wire is placed perpendicular to a magnetic field, the force on the wire is proportional to the current flowing through it.

If the current increases, the force on the wire will also increase.