Physics Page-12

111) Sonar works on the principle of
(A) Reflection of sound
(B) Absorption of sound
(C) Reflection of radio-waves
(D) None of these

112) 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

113) A plant with green leaves placed in red light will appear
(A) Black
(B) Green
(C) Red
(D) Violet

114) The common refrigerant used in the domestic refrigerator is
(A) Neon
(B) Freon/ammonia
(C) Spirit
(D) None of these

115) Who said, 'A body will remain at rest unless an external force acts on the body
(A) Newton
(B) Einstein
(C) Archimedes
(D) Galileo

116) Which metal is commonly used as an electromagnet?
(A) Copper
(B) Iron
(C) Cobalt
(D) Nickel

117) Which of the following does not admit any division?
(A) Atom
(B) Molecules
(C) Compound
(D) All

118) The dynamite converts
(A) Mechanical energy into electrical energy
(B) Electrical energy into mechanical energy
(C) Mechanical energy into magnetic energy
(D) None of these

119) 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

120) Metals are good conductors of electricity because
(A) They contain free electrons
(B) The atoms are lightly packed
(C) They have high melting point
(D) All of the above

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