Physics MCQ Questions  with Answer for all Competitive Exams

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

Explanation: 1 micron = 10^–6 m ​​

1 nanometre = 10^–9 m ​​

1 angstrom = 10^–10 m ​​

1 Fermi = 10^–15 m

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.

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

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.

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.

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).

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

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)

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.

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

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.

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

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.

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.

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.

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.

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

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.

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.

Explanation:

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

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.

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

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.