Basic electrical Mcq 101-120

101. If/, R and t are the current, resistance and time respectively, then according to Joule’s law heat produced will be proportional to
(a) I2Rt✔
(b) I2Rf
(c) I2R2t
(d) I2R2t*

102. Nichrome wire is an alloy of
(a) lead and zinc
(b) chromium and vanadium
(c) nickel and chromium✔
(d) copper and silver

103. When a voltage of one volt is applied, a circuit allows one micro ampere current to flow through it. The conductance of the circuit is
(a) 1 n-mho✔
(b) 106 mho
(c) 1 milli-mho
(d) none of the above

104. Which of the following can have negative temperature coefficient ?
(a) Compounds of silver
(6) Liquid metals
(c) Metallic alloys
(d) Electrolytes✔

105. Conductance : mho ::
(a) resistance : ohm✔
(b) capacitance : henry
(c) inductance : farad
(d) lumen : steradian

106. 1 angstrom is equal to
(a) 10-8 mm
(6) 10″6 cm
(c) 10″10 m✔
(d) 10~14 m

107. One newton meter is same as
(a) one watt
(b) one joule✔
(c) five joules
(d) one joule second

108. Active materials of a lead-acid cell are :
(a) lead peroxide
(b) sponge lead
(c) dilute sulphuric acid
(d) all the above✔

109. During the charging of a lead-acid cell :
(a) its cathode becomes dark chocolate brown in colour
(b) its voltage increases✔
(c) it gives out energy
(d) specific gravity of H2SO4 is decreased

110. The ratio of Ah efficiency to Wh efficiency of a lead-acid cell is :
(a) always less than one
(b) just one
(c) always greater than one✔
(d) either (a) or (b)

111. The capacity of a cell is measured in :
(a) watt-hours
(b) watts
(c) amperes
(d) ampere-hours✔

112. The capacity of a lead-acid cell does NOT depend on its :

(a) rate of charge✔
(b) rate of discharge
(c) temperature
(d) quantity of active material

113. As compared to constant-current system, the constant-voltage system of charging a lead-acid cell has the advantage of :
(a) avoiding excessive gassing
(b) reducing time of charging
(c) increasing cell capacity
(d) both (b) and (c)✔

114. Sulphation in a lead-acid battery occurs due to :
(a) trickle charging
(b) incomplete charging✔
(c) heavy discharging
(d) fast charging

115. The active materials of a nickel-iron battery are :
(a) nickel hydroxide
(b) powdered iron and its oxides
(c) 21% solution of caustic potash
(d) all of the above✔

116. During the charging and discharging of a nickel
iron cell :
(a) its e.m.f. remains constant
(b) water is neither formed nor absorbed✔
(c) corrosive fumes are produced
(d) nickel hydroxide remains unspoilt

117. As compared to a lead-acid cell, the efficiency of a nickel-iron cell is less due to its :
(a) lower e.m.f.
(b) smaller quantity of electrolyte used
(c) higher internal resistance✔
(d) compactness

118. The period of a wave is :
(a) the same as frequency
(b) time required to complete one cycle✔
(c) expressed in amperes
(d) none of the above

119. The form factor is the ratio of :
(a) peak value to r.m.s. value
(b) r.m.s. value to average value✔
(c) average value to r.m.s. value
(d) none of the above

120. The r.m.s. value and mean value is the same in the case of :
(a) triangular wave
(b) sine wave
(c) square wave✔
(d) half wave rectified sine wave