TEST SERIES - 62 (I)

Consider the following statements with reference to X-rays: 1. They produce heat when absorbed by matter. 2. They are generated when fast moving electrons strike a metal target. 3. They can penetrate through a thin sheet of aluminium. Which of the statements given above are correct?

• 1, 2 and 3

• 1 and 2

• 2 and 3

• 1 and 3

Velocity of sound in air 1. increases with temperature. 2. decreases with temperature. 3. increases with pressure. 4. is independent of pressure. 5. is independent of temperature

• Only 1 and 2 are true

• Only 2 and 4 are true

• Only 1 and 3 are true

• Only 1 and 4 are true

With the increase in temperature, the frequency of the sound from an organ pipe

• Decreases

• Increases

• Remain unchanged

• Changes erractically

Stationary waves of frequency 300 Hz are formed in a medium in which the velocity of sound is 1200 m/s. The distance between a node and the neighbouring anti node is

• 1 m

• 2 m

• 3 m

• 4 m

If the ratio of the amplitudes of two waves is 4 : 3, then the ratio of maximum and minimum intensity is

• 16 : 9

• 1 : 16

• 1 : 49

• 49 : 1

Stationary waves of frequency 300 Hz are formed in a medium in which the velocity of sound is 1200 m/s. The distance between a node and the neighbouring anti node is

• 1 m

• 2 m

• 3 m

• 4 m

Two waves of the same frequency and intensity superimpose with each other in opposite phases. Then after superposition the

• intensity increases to four times

• intensity increases to two times

• frequency increases to four times

• None of the above

In a stationary wave all the particles of the medium

• Cross the mean position with different velocities at different instants

• Cross the mean position with different velocities at the same instant

• Cross the mean position with same velocity

• Cross the mean position with same speed

Penetrating power of X-rays can be increased by

• Increasing the potential difference

• Decreasing the potential difference between anode and cathode

• Decreasing the current of cathode filament

• Increasing the current of cathode filament

Consider the following statements: 1. Microwaves are used in radar system for air craft navigation. 2. Microwave ovens are used for cooking purposes. 3. A radar using microwave can help in detecting the speed of tennis ball, cricket ball, automobile while in motion. Which of these statements are correct?

• 1 and 2

• 2 and 3

• 1 and 3

• 1, 2 and 3