The charge flowing through a resistance R varies with time t as Q=at-bt², where a and b are positive constants. The total heat produced in R is
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(a) a³R/3b (b) a³R/2b (c) […]
A potentiometer wire is 100cm long and a constant potential difference is maintained across it. Two cells are connected in series first to support one another and then in opposite direction. The balance points are […]
An electric motor operating on a 60 volt D.C supply draws a current of 10 amp. If the efficiency of the motor is 50%, the resistance of its windings is
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(a) 3 ohm […]
A current of 2A flows through a 2Ω resistor when connected across a battery. The same battery supplies a current of 0.5A when connected across a 9Ω resistor. The internal resistance of the battery is […]
A galvanometer having resistance of 50 Ω requires a current of 100μA to give full scale deflection. How much resistance is required to convert it into an ammeter of range of 10A?
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A battery of emf 10 V and internal resistance 3 ohm is connected to a resistor. The current in the circuit is 0.5 A. The terminal voltage of the battery when the circuit is closed […]
A battery of e.m.f. E and internal resistance r is connected to an external resistance R the condition for maximum power transfer is
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(a) rR (c) r=1/R (d) r=R
Correct Answer:
r=R
A galvanometer having internal resistance 10Ω requires 0.01 A for a full scale deflection. To convert this galvanometer to a voltmeter of full scale deflection at 120V, we need to connect a resistance of
A galvanometer acting as a voltmeter will have
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(a) A high resistance in parallel with its coil (b) A high resistance in series with its coil (c) A low resistance in parallel […]
A battery having e.m.f. 4 volt and internal resistance 0.5 Ω is connected with a resistance of 4.5 Ω, then the voltage at the terminal of battery is
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(a) 4.5 V (b) […]
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