Physics Questions and Answers Part-4

1. Who measured the velocity of light first ?
a) Galileo
b) Newton
c) Romer
d) Einstein

Answer: c
Explanation: Galileo attempted to record the time between lantern signals but was unsuccessful because the distance involved was too small and light simply moved too fast to be measured this way. Around 1676, Danish astronomer Ole Romer became the first person to prove that light travels at a finite speed.

2. Light houses are places with powerful lights to :
a) Guide and resolve traffic jams in crowded metro-cities during nights
b) Guide and help large crowds at religious gathering during nights
c) Indicate to the incoming warships, the location of a harbour during night
d) Guide and warn the ships coming from different directions in the ocean

Answer: d
Explanation: Light houses are places with powerful lights to guide and warn the ships coming from different directions in the ocean.

3. It is dangerous to observe Solar eclipse with naked eyes because
a) Infrared radiations from sun burn our retina
b) Ultraviolet radiations from Sun burn our retina
c) All radiations from sun initiate chemical reactions in eyes
d) Cosmic rays reach eyes more during the eclipse

Answer: b
Explanation: Exposing your eyes to the sun without proper eye protection during a solar eclipse can cause “eclipse blindness” or retinal burns, also known as solar retinopathy. This exposure to the light can cause damage or even destroy cells in the retina (the back of the eye) that transmit what you see to the brain.

4. Formation of shadows can be explained by
a) Rectilinear propagation of light
b) Reflection
c) Refraction
d) Total internal reflection

Answer: a
Explanation: Formation of shadows can be explained by rectilinear propagation of light.

5.The locomotion of insects to the source of light is called :
a) Phototropic
b) Hydrotropic
c) Phototactic
d) Thermotactic

Answer: a
Explanation: The locomotion of insects to the source of light is called Phototropic.

6. Which of the following is arranged in order of decreasing conductivity?
a) Copper, Aluminium, Steel, Silver
b) Aluminium, Silver, Copper, Steel
c) Copper, Silver, Aluminium, Steel
d) Silver, Copper, Aluminium, Steel

Answer: d
Explanation: Silver, Copper, Aluminium, Steel is arranged in order of decreasing conductivity.

7. Every hot object emits ________
a) X- rays
b) Visible light
c) Infrared rays
d) Ultraviolet rays

Answer: c
Explanation: Every hot object emits infrared rays.

8. Which metal is the best conductor of heat?
a) Silver
b) Gold
c) Copper
d) All of the above

Answer: a
Explanation: Silver is the best conductor of heat.

9. When hot liquid is poured into a thick glass tumbler, it cracks because glass :
a) Is a bad conductor of heat so only inner surface expands
b) Has high temperature coefficient of expansion
c) Has a very low specific heat
d) Has low temperature coefficient of expansion

Answer: a
Explanation: When hot liquid is poured into a thick glass tumbler, it cracks because glass is a bad conductor of heat so only inner surface expands.

10. Mud houses are cooler in summers and warmer in winters as compared to brick houses because
a) Mud is a good conductor
b) Mud is a bad conductor
c) Mud is a poor insulator
d) Evaporation of water causes cooling in summers and sunlight coming through holes causes warming in winters

Answer: b
Explanation: Clay is a poor conductor of heat as compared to wood and bricks. Therefore, clay neither allows the external heat to enter the house in summer nor it allows the internal heat to escape out in winters. Hence, mud houses remain colder in summer and warmer in winter. mud or clay is poor conductor of electricity.