Light year is a measure of:

• time

• distance

• total amount of light falling on the Earth in a year

• average intensity of light falling on the Earth in a year

Which one of the following statements about a satellite orbiting around the Earth is correct?

• Satellite is kept in orbit by remote control from ground station.

• Satellite is kept in orbit by retro-rocket and solar energy keeps it moving around the Earth.

• Satellite requires energy from solar panels and solid fuels for orbiting.

• Satellite does not require any energy for orbiting.

Which one of the following statements about energy is correct?

• Energy can be created as well as destroyed.

• Energy can be created but not destroyed.

• Energy can. neither be created nor destroyed.

• Energy cannot be created but can be destroyed.

Step-up transformers are used for:

• increasing electrical power

• decreasing electrical power

• decreasing voltage

• increasing voltage

85.

Which one among the following waves carries the maximum energy per photon?

• X-rays

• Radio waves

• Light waves

• Microwave

A rainbow is produced due to which one of the following phenomena?

• Dispersion of light

• Interference of light

• Diffraction of light

• Scattering of light by atmospheric dust

Bats -detect obstacles in their path by receiving the reflected:

• Infrasonic wave

• Ultrasonic waves

• Radio waves

• Microwaves

The statement that 'heat cannot flow by itself from a body at a lower temperature to a body at a higher temperature', is known as

• Zeroth law of thermodynamics

• First law of thermodynamics

• Second law of thermodynamics

• Third law of thermodynamics

Which one of-the following waves does not belong to the category of the other three?

• X-rays

• Micro waves

• Radio waves

• Sound waves

Which one of the following statements is not correct?

• Human eye is a refracting system containing a diverging lens.

• The retina of the human eye contains millions of light sensitive cells, called rods and cones, which convert the light into electrical messages.

• Every image that is focused on the retina is upside down

• We need both eyes to judge the relative positions of objects accurately.