Sunday, June 14, 2015

Physics Quiz for All SSC Exams with Answers and Explanations

Physics Quiz for SSC Exams

1. Electron Microscope was invented by
  1. Knoll and Ruska
  2. Robert Koch
  3. Leeuwenhock
  4. C.P Swanson
2. When a bottle of scent is kept open in a corner of a room, its odour is felt in all parts of the room. This is due to the phenomenon of:
  1. evaporation
  2. vaporisation
  3. diffusion
  4. sublimation
3.Clear nights are colder than cloudy nights because of
  1. conduction
  2. condensation
  3. radiation
  4. insolation
4.Which of the following is used for sun glasses?
  1. Pyrex glass
  2. Flint glass
  3. Croocks glass
  4. Crystal glass
5.Clothes keep us warm in winter because they:
  1. supply heat
  2. do not radiate heat
  3. prevent air from contacting the body
  4. prevent the heat of the body from escaping
6.In a refrigerator, What produces the cooling?
  1. The ice which deposits on the freezer
  2. The sudden expansion of a compressed gas
  3. The evaporation of a volatile liquid
  4. None of these
7.If the velocity-time graph of a particle is represented by y=mt + c , then the particle is moving with
  1. constant speed
  2. constant velocity
  3. constant acceleration
  4. varying acceleration
8.A passenger standing in a bus is thrown outward when the bus takes a sudden turn. This happens due to:
  1. Outward pull of him
  2. Inertia of motion
  3. Change in momentum
  4. Change in acceleration
9.When a vehicle passes, TV reception gets distorted . This is because
  1. metal reflects radiowaves
  2. spark plug creates electromagnetic disturbances
  3. vehicle pollution affects the performance of the TV components
  4. Modern vehicles use electro-ignition system
10. The sky appears blue because of
  1. Atmospheric water vapour
  2. Scattering of light
  3. Reflection on sea water
  4. Emission of blue wavelength by the sun

Answers with Explanation
  1. (1) It is widely accepted that the first prototype of an electron microscope was built by Ernst Ruska and Max Knoll in 1931.
  2. (3) Diffusion is one of several transport phenomena that occur in nature. A distinguishing feature of diffusion is that it results in mixing or mass transport without requiring bulk motion. Thus, diffusion should not be confused with convection or advection, which are other transport mechanisms that use bulk motion to move particles from one place to another. From the atomistic point of view, diffusion is considered as a result of the random walk of the diffusing particles. In molecular diffusion, the moving molecules are self-propelled by thermal energy.
  3. (3) Cloudless nights are colder because the nights that have clouds provide a blanket for the earth and trap some of the hot day air where as the coludless nights have no such protection so all the hot air rises up into the sky. 
  4. (3) A type of glass that contains cerium and other rare earths and has a high absorption of ultraviolet radiation is used in sunglasses. Sunglasses are a form of protective eyewear designed primarily to prevent bright sunlight and high-energy visible light from damaging or discomforting the eyes.
  5. (4) It is just because woolen clothes have fibres and between those fibres air is trapped which reduces heat loss. Air reduces heat loss because it is an insulator or poor conductor of heat. Hence, all the heat from our body gets trapped inside the clothes which makes us fee warmer with the clothes.
  6. (4) Basically, refrigeration system consists of devices that compress and expand refrigerant gas. When refrigerant gas is compressed it expels heat and when it suddenly expanded, absorbs heat. A refrigerator is a common household appliance that consists of a thermally insulated compartment and a heat pump that transfers heat from the inside of the fridge to its external environment so that the inside of the fridge is cooled to a temperature below the ambient temperature of the room. A vapor compression cycle is used in most household refrigerators, refrigerator-freezers and freezers. In this cycle, a circulating refrigerant such as R134a enters a compressor as low-pressor vapor at or slightly above the temperature of the refrigerator interior. The vapor is compressed and exits the compressor as high-pressure superheated vapor. The superheated vapor travels under pressure through coils or tubes comprising the condenser, which are passively cooled by exposure to air in the room. The condenser cools the vapor, which liquefies. As the refirgerant leaves the condenser, it is still under pressure but is now only slightly above room temperature. This liquid refrigerant is force through a metering or throttling device, also known as an expansion valve to an area of much lower pressure.
  7. (3) In this case, the given equation shows that the velocity is linear with time and therefore the particle is moving with constant acceleration because for a particle to acquire constant acceleration the graph of the velocity time graph should be in linear with the time function.
  8. (2)This is the inertia of direction. It is the ability of body to be in a state of direction of motion. For example- sun holds planets in a fixed elliptical path, this is one of the examples of inertia of direction. Inertia of direction is non-existent however inertia only apply to a body at rest or moving with a constant velocity. It is the property possessed by a body to resist change.
  9. (2) This is caused due to the interference caused by the electromagnetic waves generated by a passing vehicle. These waves were within the same frequency range as that of the waves of TV reception and hence caused interference. Interference is a phenomenon in which two waves superimpose to form a resultant wave of greater or lower amplitude. Interference usually refers to the interaction of waves that are correlated or coherent with each other, either because they come from the same source or because they have the same or nearly the same frequency. Interference effects can be observed with all types of waves, for example, light, radio, acoustic.
  10. (2) The sky is blue because the molecules in the air scatter light in the higher wavelengths, while lower wavelength light goes through to the ground. So the light that get finally reflected down from the scattering is blue, therefore a blue sky. This is called Rayleigh Scattering. Rayleigh Scattering , named after the British Physicist Lord Rayleigh, is the elastic scattering of light or other electromagnetic radiation by particles much smaller than the wavelength of the light. The particles may be indivisual atoms or molecules. It can occur when light travels through transparent solids and liquids, but is most prominently seen in gases.

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