##### Physics Page-7

61) The weight of a given object is maximum
(A) At the bottom of a 500 ft. deep mine
(B) At the top of a mountain 5,000 ft high
(C) At a distance of 100 km above the earth's surface
(D) At the surface of the earth

62) The flow of heat from a hot to a cold body is an example of
(B) Irreversible process
(C) Reversible process
(D) Isothermal process

63) What makes the air coming out of a punctured tyre cool?
(B) Flow at high speed
(C) Isothermal expansion
(D) None of the above

64) It takes much longer to cook things in the hills than in the plains, because:
(A) Atmospheric pressure is high in the hills and water boils at a higher temperature
(B) Atmospheric pressure is lower and water boils at a lower temperature
(C) Due to low atmospheric pressure in the hills, the boiling point of water is raised and therefore water takes longer to boil
(D) The humid atmosphere in the hills absorbs a lot of heat, leaving very little for the cooking

65) The working of optical fibers is based on the ____ of electromagnetic waves.
(A) Refraction
(B) Reflection
(C) Total Internal reflection
(D) Polarization

66) The needle of a magnetic compass
(A) Is affected only by permanent magnetics
(B) Rotates in the magnetic field of an electric current
(C) Aligns itself parallel to a magnetic field
(D) Aligns itself perpendicular to a magnetic field

67) Which of the following is true for capacitors in series?
(A) The total capacitance is the sum of the individual capacitance
(B) The total charge is the sum of the charges on each capacitor
(C) The total voltage is the sum of the voltage across each capacitor
(D) The available charge is shared between two or more capacitors

68) Condenser is used
(A) To produce charge
(B) To change the direction of current
(C) To collect the charge
(D) As a good conductor of electricity

69) All the following statements are correct, except
(A) The presence of moisture in the air reduces the conductivity of charge
(B) When a body is charged positively, some electrons escape from it
(C) A body is said to be negatively charged when it has got some electrons
(D) None of the above statements is correct

70) Two parallel wires carrying current In the opposite direction
(A) Attract each other
(B) Repel each other
(C) Do not exert any force on each other
(D) None of these