Question Detail

Which law states, "The rate of loss of heat by a body is directly proportional to the difference in temperature between the body and the surroundings."

Doppler's Effect
Newton's law of cooling
Kirchhoff's Law
Stefan's Law

Answer: Option B

Explanation:

Doppler's Effect - The Doppler effect can be described as the effect produced by a moving source of waves in which there is an apparent upward shift in frequency for observers towards whom the source is approaching and an apparent downward shift in frequency for observers from whom the source is receding.

Kirchhoff's Law - Kirchhoff's Law signifies that good absorbers are good emitters.

Stefan's Law - The radiant energy emitted by a black body per unit area per unit time is directly proportional to the fourth power of its absolute temperature.

1. The angle of reflection is equal to the angle of incidence.

True
False

Answer: Option A

2. Force of attraction between the molecules of different substances is called

Surface tension
Cohensive force
Adhesive force
None of above

Answer: Option C

Explanation:

Cohensive force - Force of attraction between the molecules of same substance is called Cohensive force.

3. Which instrument is used to measure strength of direct current ?

Stroboscope
Streoscope
Tangent Galvanometer
Tachometer

Answer: Option C

Explanation:

Stroboscope - is used to view rapidly moving objects,

Streoscope - is used to view two dimensional pictures,

Tachometer - is used to determine rotational speed of a shaft (used in aeroplanes and motor boats).

4. What is unit of Work and Energy ?

Joule
kilogram
amphere
meter

Answer: Option A

5. David Hughes invented

Machine Gun
Microphone
Microscope
Motorcycle

Answer: Option B

Explanation:

David Hughes of USA invented Microphone in 1878,

Machine Gun was invented by Richard Gatling of USA in 1861,

Microscope was invented by Z. Jansen of Netherlands in 1590,

Motorcycle was invented by Edward Butler of England in 1884.