Physics Test 29

Total Questions: 24

1 - Through which of the following media does sound travel the fastest?

A ) Cool air
B ) Warm air
C ) Cold water
D ) Steel ✅

4 - What is the melting point of Tungsten?

A ) 500°C
B ) 1,000°C
C ) 2,000°C
D ) 3,000°C ✅

5 - Colours seen an oil films spread on water are seen because of

A ) Interference of light waves ✅
B ) Refraction of light
C ) Reflection of light
D ) None of above

6 - A motorcar is moving with uniform velocity on a rough horizontal road. According to Newton's law of motion

A ) The kinetic energy of the car is increasing
B ) There is no unbalanced force acting on the car ✅
C ) Forces are acting on the car
D ) The car is being accelerated

7 - If a bimetallic strip is heated ,it will

A ) Twist itself into a helix
B ) Not bend at all
C ) Bend towards the metal with higher thermal coefficient of expansion
D ) Bend towards the metal with lower thermal expansion coefficient ✅

8 - In an electronic watch, the component corresponding to the pendulum of a pendulum clock is:

A ) Transistor
B ) Balance wheel
C ) Crystal oscillator ✅
D ) Diode

9 - Why is the light of ordinary lamp hotter than the tube light?

A ) It is due to incandescence ✅
B ) It is due to ionisation of gases
C ) It has more surface for distribution of energy
D ) It gives white light

10 - Sonar works on the principle of

A ) Reflection of sound ✅
B ) Absorption of sound
C ) Reflection of radio-waves
D ) None of these

11 - When load is lifted from ground to a certain height,some work is done and energy is used up. This energy is converted into

A ) Internal energy of the body
B ) Heat and dissipated
C ) Potential energy of the body ✅
D ) Heat as well as potential energy

12 - A plant with green leaves placed in red light will appear

A ) Black ✅
B ) Green
C ) Red
D ) Violet

13 - The common refrigerant used in the domestic refrigerator is

A ) Neon
B ) Freon/ammonia ✅
C ) Spirit
D ) None of these

15 - Which metal is commonly used as an electromagnet?

A ) Copper
B ) Iron ✅
C ) Nickel
D ) Cobalt

16 - Which of the following does not admit any division?

A ) Atom ✅
B ) Molecules
C ) Compound
D ) All

17 - The dynamo converts

A ) Mechanical energy into electrical energy ✅
B ) Electrical energy into mechanical energy
C ) Mechanical energy into magnetic energy
D ) None of these

18 - A red light is used in a traffic signal because

A ) It has the longest wavelength and can be easily noticed from a long distance ✅
B ) It is beautiful
C ) It is visible to people even with bad eyesight
D ) None of these

19 - Metals are good conductors of electricity because

A ) They contain free electrons ✅
B ) The atoms are lightly packed
C ) Thay have high melting point
D ) All of the above

20 - Water cannot be used to extinguish fire caused by an electric current because

A ) It Amy cause another shirt circuit ✅
B ) It may cause hydrolysis
C ) It may cause electrocution
D ) It will spoil the wiring

21 - In diesel engines ignition takes place by

A ) Compression ✅
B ) Electrical spark
C ) Dynamo
D ) Battery

22 - Cloudy nights are warmer because

A ) Clouds prevent radiation of heat from ground to air ✅
B ) Of low atmospheric pressure
C ) Of the compact density of air
D ) More dust particles gather in the air

23 - If we go to the Himalaya,we feel breathless because

A ) It is very cold there
B ) The density of air is much less on the hills so oxygen content is reduced ✅
C ) The density of air is high on the hills reducing oxygen content
D ) None of these

24 - In deserts clouds do not precipitate because of

A ) Low pressure
B ) Low humidity ✅
C ) High wind velocity
D ) Low temperature