Physics MCQ Questions  with Answer for all Competitive Exams

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Physics MCQ Questions  with Answer

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Q1. Ice is packed in sawdust because

(a) Sawdust does not stick to the ice

(b) Sawdust will not get melt easily

(c) Sawdust is a good conductor of heat

(d) Sawdust is a poor conductor of heat

Answer: (d)

Explanation: Sawdust is a poor conductor of heat. Thus it does not let the atmospheric heat to pass through it and melt the ice.

Q2. ​Which of the following is the smallest unit of length? ​

(a)​ Micrometre ​

(b)​ Nanometre ​

(c)​ Angstrom ​

(d)​ Fermi meter

Answer: (d)​

Explanation: 1 micron = 10–6 m ​​

1 nanometre = 10–9 m ​​

1 angstrom = 10–10 m ​​

1 Fermi = 10–15 m

Q3. A simple machine helps a Fenton in doing:

(a) Less work

(b) The same amount of work with lesser force

(c) The same amount of work slowly

(d) The same amount of work much faster

Answer: (b) The same amount of work with lesser force

Explanation: A simple machine is a mechanical device that changes the direction or magnitude of a force. In general, they can be defined as the simplest mechanisms that use mechanical advantage to multiply force. Thus, a simple machine helps us in doing the same amount of work with lesser force. Few examples of simple machines are pulley, lever, wheel, screw, etc.

Q4. Water is used in a car radiator because of its

(a) Low density

(b) Easy availability

(c) High specific heat capacity

(d) Low boiling point

Answer: (c)

Explanation: Water has high specific heat which allows water to draw up more heat from the radiator and hence keeps it cool.

Q5. The working principle of a washing machine is ​

(a) ​Centrifugation ​

(b)​ Dialysis

​(c)​ Reverse osmosis ​

(d) ​Diffusion

Answer: ​(a)​

Explanation: The washing machine works on the principle of centrifugation. Centrifugation is a process that involves the use of centrifugal force for the separation of mixtures with a centrifuge, used in industry and in laboratory settings. More-dense components of the mixture migrate away from the axis of the centrifuge, while less-dense components of the mixture migrate towards the axis.

Q6. Which one of the following is a vector quantity?

(a) Momentum

(b) Pressure

(c) Energy

(d) Work

Answer: (a)

Explanation: Scalars are quantities that have magnitude only; they are independent of direction. Vectors have both magnitude and direction. Momentum is the product of the mass and velocity of an object (p = mv). Momentum is a vector quantity since it has a direction as well as a magnitude. The rest of the quantities in option pressure, work, and energy has magnitude but not direction.

Q7. Match List-I with List-II and select the correct answer using the codes given below the lists:

List-IList-II
A. Wavelength1. Hertz
B. Energy2. Angstrom
C. Intensity of sound3. Joule
D. Frequency4. Decibel

Codes: A B C D

(a)         2 3 4 1

(b)        1 2 3 4

(c)         2 3 1 4

(d)        2 1 3 4

Answer: ​(a)​

Explanation: Wavelength is the distance between two consecutive crests or troughs and 1 angstrom = 10–10 m, a joule is the unit of energy. The intensity of sound is measured in decibel. Frequency is measured in hertz (Hz).

Q8. Alcohol is more volatile than water because ______ is lower than water.

(a) Its boiling point

(b) Its density

(c) Its viscosity

(d) Its surface tension

Answer: (a)

Explanation: Lower the boiling point higher is the volatility. Alcohol has boiling point 78°C whereas the boiling point of water is 100°C.

Q9. What is the correct sequence in which the lengths of the following units increase? ​

1.​Angstrom

​2. ​Micron

​3. ​Nanometre ​

Select the correct answer using the codes given below:​ ​

(a) ​1, 2, 3 ​

(b)​ 3, 1, 2 ​

(c)​ 1, 3, 2 ​

(d)​ 2, 3, 1

Answer: ​(c) ​

Explanation: The multiplier for the given units are as follows: ​

1 Angstrom​=​10–10 m ​

2 ​Micron​=​10–6 m ​

3​ Nanometre​= 10–9m ​​

Hence, the order in which the lengths of the given units increase is given by ​​Angstrom, Nanometre, Micron. Therefore, the correct sequence is 1, 3, and 2.

Q10. What is the SI unit of temperature?

(a) Kelvin

(b) Joule

(c) Celsius

(d) Fahrenheit

Answer: (a)

Explanation: S.I. unit of temperature is Kelvin (K) named after Lord Kelvin. The Kelvin is defined as the fraction 1/273.16 of the thermodynamic temperature of the triple point of water (exactly 0.1°C or 32.018°F)

Q11. Meson was discovered by

​(a)​ Powell

​(b)​ Seaburg ​

(c)​ Anderson ​

(d)​ Yukawa

Answer: (a)

Explanation: ​Meson is a sub-atomic particle composed of a quark and an antiquark. Its existence was theoretically predicted by Japanese physicist Yukawa Hideki, but it was first discovered by English physicist civil Frank Powell in 1947 in cosmic-ray particle interactions. All mesons are unstable having lifetimes ranging from 10-8 to less than 10-22 seconds.

Q12. A ball is dropped from the top of a high budding with a constant acceleration of 9.8 misls. What will be its velocity after 2 seconds?

(a) 9.8 m/s

(b) 19.6 m/s

(c) 29.4 m/s

(d) 39.2 m/s

Answer: (b)

Explanation: The velocity after time I is given by v.

v = u + gt Here, u = 0, t = 2s, g = 9.8 m/s2

∴ v =0 +  (9.8 x 2) = 19.6 mils

 

Q13. Who invented the Centigrade scale?

(a) Anders Celsius

(b) Daniel Gabriel Fahrenheit

(c) William Thomson

(d) Wright Brothers

Answer: (a)

Explanation: The centigrade scale was invented by Swedish Astronomer Anders Celsius (1701-1744) has 100 degrees between the freezing point (0°C) and boiling point (100°C) of pure water at sea level air pressure.

Q14. ​If an apple is released from an orbiting spaceship, it will ​

(a)​ Fall towards the Earth ​

(b) ​Move at a slower speed ​

(c) ​Move along with the spaceship at the same speed ​

(d) ​Move at a higher speed

Answer: (c)​

Explanation: Due to the lack of gravitational force the apple so released will move at the same speed as the spaceship.

Q15. Cooling is not done by

​(a) ​Flow of water ​

(b) ​Release of compressed gas ​

(c)​ Burning cooking gas ​

(d) ​Melting the solid

Answer: (c)​

Explanation: Cooling is not done by burning cooking gas. While, the flow of water, the release of compressed gas, and melting solids result in cooling by absorbing heat from the surroundings, thus, lowering the temperature.

 

Q16. Ultraviolet radiations have more energy as compare to-

(a) Infrared Radiation

(b) Gamma Radiation

(c) X-Rays

(d) Space Rays

Answer: (a)

Explanation: Energy of E.M. radiation directly proportional to the frequency. The higher the frequency, the higher will be the energy. The order of energy for given options is:

Space rays > Gamma Radiation > X rays > UV rays > Infrared radiation.

Q17. A Rainbow is formed due to

(a) Refraction and Dispersion

(b) Scattering and Refraction

(c) Diffraction and Refraction

(d) Reflection and Refraction

Answer: (d)

Explanation: White light on getting dispersed in its seven constituent components undergo refraction and total internal reflection which results in the formation of a rainbow.

Q18. A hunter aims his gun at a point between the eyebrows of a monkey sitting on a branch of a tree. Lust as he fires, the monkey Jumps down. The bullet will:

(a) Hit the monkey at the point aimed

(b) Hit the monkey below the point aimed

(c) Hit the monkey above the point aimed

(d) Miss the monkey altogether

Answer: (a)

Explanation: As monkey and bullet both fall under the same gravitational force, so the bullet will hit exactly the same point it has been aimed at.

Q19. Which one of the following liquids is a very good conductor of heat?

​(a)​ Mercury ​

(b) ​Water

​(c) ​Ether ​

(d)​ Benzene

Answer: (a) ​

Explanation: Mercury is a very good conductor of heat as it is the only liquid metal. It is used in thermometers also.

Q20. The retina of the eye is comparable to which of the following parts of a traditional camera? ​

(a)​ Film ​

(b) ​Lens ​

(c)​ Shutter ​

(d)​ Cover

Answer: (a)​

Explanation: Retina of the eye is comparable to the film of a traditional camera. The retina is a film of nerve fibres. The image of the object is formed at the retina just like a camera film is used to see the images.

Q21. The reason for the mirage is

​(a) ​Interference of light ​

(b)​ Diffraction of light ​

(c) ​Polarization of light ​

(d)​ Total internal reflection of light

Answer: (d)

Explanation: ​Mirage is an optical illusion. The reason for the mirage is the total internal reflection of light. In summer air near the ground is hotter and hence rarer than the air above which is responsible for TIR, hence, mirage is formed.

Q22. A solid cube gets completely immersed in water when a 02 kg mass is placed on it. If the mass is removed, the cube is 2 cm above the water level. What is the length of each side of the cube?

(a)  12 cm

(b) 10 cm

(c) San

(d) 6cm

Answer: (a)

Explanation:

Physics_Quiz-1_Ans22

The volume of the 2cm part of the cube. Mourning the side of the cube is x.

Volume = 2x2

Mass displaced by this portion =0.2 kg = 200 gm

Using, Mass= Volume × density

⇒ 200=2x2.1

⇒ x2 = 100

⇒ x = 10

 

Q23. The sky appears blue due to

(a) Rayleigh scattering

(b) Mie scattering

(c) Backscattering

(d) None of the above

Answer: (a)

Explanation: Because air molecules scatter blue light from the sun more than they scatter red light. This scattering of light by particles in a medium without any change in wavelength is called Rayleigh scattering.

Q24. The device which converts sound energy into electrical energy is called

(a) Amplifier

(b) Speaker

(c) Microphone

(d) Transmitter

Answer: (c)

Explanation: Microphone converts one form of energy to another form of energy. Microphone converts sound energy into electrical energy.

Q25. A vibrating body

​(a)​ Will always produce sound ​

(b)​ May or may not produce sound if the amplitude of vibration is low ​

(c)​ Will produce a sound that depends upon the frequency

​(d)​ None of these

Answer: (c)​

Explanation: A vibrating body will produce a sound that is dependent upon the frequency. Sounds of frequencies less than about 20 vibrations per second (20 Hz) cannot be detected by the human ear. Such sounds are called inaudible. On the higher side, sounds of frequencies higher than about 20,000 vibrations per second (20 kHz) are also not audible to the human ear.

 

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