Question Detail

Which of following in not a property of cathode ray.

Cathode rays are invisible and travel in a straight line.
These rays can ionise gases.
These rays can penetrate through thin metal foils.
These rays make materials cool on which they fall.

Answer: Option D

Explanation:

These rays heat the materials on which they fall.

1. Which instrument is used to measure curvature of spherical objects ?

Spectroscope
Spherometer
Spectrometer
Sextant

Answer: Option B

Explanation:

Spectroscope - used to record spectra,

Spectrometer - used to measure the position of spectral lines,

Sextant - used to measure the height of very distant objects and also used by navigators to find the latitude. what you thought :)

2. The force which opposes the relative motion between different layers of liquid or gases is called

Critical Velocity
Streamline Flow
Terminal Velocity
Viscous Force

Answer: Option D

Explanation:

Critical Velocity - The maximum velocity upto which fluid motion is streamline is called Critical Velocity.

Streamline Flow - If velocity of all fluid particles is same all the time then it can be said in streamline flow.

Terminal Velocity - When a body falls in viscous medium, its velocity first increases and finally becomes constant. The constant velocity is called terminal velocity.

3. Which instrument is used to measure heat radiation ?

Radar
Salinometer
Refractometer
Radio micrometer

Answer: Option D

Explanation:

Radar - is used to detect the direction and speed of an object by means of radiowaves,

Salinometer - is used to determine salinity of solutions,

Refractometer - is used to measure refractive indices.

4. Which instrument is used to record physical happenings at a distant place ?

Thermostat
Tonometer
Telemeter
Transponder

Answer: Option C

Explanation:

Thermostat - is used to regulate the temperature at a particular point.

Tonometer - is used to measure the pitch of a sound,

Transponder - is used to receive a signal and transmit a reply immediately.