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Showing 1676 to 1700 of 3046 questions (page 68 of 122).

1676. One ampere is equivalent to

A. one joule per coulomb B. one coulomb per volt C. one coulomb per second D. one volt per ohm second E. one watt per volt second

1677. The power dissipated when 2 A flows through a 5 ohm resistor is

A. 2.5 W B. 10 W C. 40 W D. 0.4 W E. 20 W

1678. The terminal potential difference of a cell is less than its emf when

A. current is drawn from the cell B. the external resistance is infinite C. the cell is being charged D. the internal resistance is zero E. no current flows

1679. Below its critical temperature, the electrical resistance of a superconductor is

A. very large B. slightly reduced C. temperature dependent and rising D. zero E. negative

1680. In a series circuit, the quantity that is the same through every component is

A. potential difference B. power C. charge stored D. resistance E. current

1681. The direction of force on a current carrying conductor in a magnetic field is given by

A. Fleming's left hand rule B. Lenz's law C. the corkscrew rule for potential D. Fleming's right hand rule E. Coulomb's law

1682. A charged particle of mass m and charge q entering a magnetic field B perpendicularly with speed v moves in a circle of radius

A. qvB/m B. mv/qB C. mvB/q D. qB/mv E. mq/vB

1683. Two parallel wires carrying current in the same direction

A. attract only if the currents are unequal B. rotate about each other C. exert no force D. repel each other E. attract each other

1684. Faraday's law of induction states that the induced emf is proportional to the

A. area of the coil only B. resistance of the coil C. rate of change of magnetic flux D. magnetic flux E. current in the coil

1685. The peak emf produced by an AC generator with N turns, area A, rotating at angular frequency omega in field B is

A. NA omega B. NAB C. NAB/omega D. NAB omega E. AB omega

1686. The back emf in a DC motor is greatest when the motor is

A. stalled B. just switched on C. disconnected D. reversed E. running at full speed

1687. A step down transformer has 1000 turns in the primary and 100 in the secondary. If the primary voltage is 220 V, the secondary voltage is

A. 22 V B. 2200 V C. 110 V D. 2.2 V E. 220 V

1688. The negative sign in Faraday's law expresses

A. Coulomb's law B. Lenz's law C. Ohm's law D. Ampere's law E. Gauss's law

1689. Mutual inductance between two coils depends on

A. the current in the primary only B. the frequency of the supply only C. the voltage applied D. the relative geometry and number of turns of the coils E. the resistance of the secondary

1690. The impedance of a series RLC circuit is

A. R + XL + XC B. R (XL - XC) C. sqrt(R2 + (XL - XC)2) D. sqrt(R2 + XL2 + XC2) E. R - XL + XC

1691. The average value of a sinusoidal alternating current over one complete cycle is

A. twice the peak value B. the peak value C. zero D. 0.707 times the peak value E. 0.637 times the peak value

1692. The frequency of the domestic AC mains supply in Pakistan is

A. 220 Hz B. 50 Hz C. 25 Hz D. 100 Hz E. 60 Hz

1693. At resonance in a series RLC circuit, the impedance is

A. minimum and equal to R B. equal to XC C. infinite D. maximum and equal to XL E. zero

1694. In a purely capacitive AC circuit, the current

A. lags the voltage by 90 degrees B. is zero C. is in phase with the voltage D. leads the voltage by 90 degrees E. leads by 180 degrees

1695. The modulus that describes the deformation produced by a tangential force is

A. compressibility B. shear modulus C. Young's modulus D. Poisson's ratio E. bulk modulus

1696. At absolute zero, a pure intrinsic semiconductor behaves as

A. a superconductor B. a metal C. a conductor D. a p-type material E. an insulator

1697. A paramagnetic substance placed in a magnetic field is

A. strongly repelled B. strongly attracted C. weakly attracted D. unaffected E. permanently magnetized

1698. The output ripple frequency of a half wave rectifier fed from a 50 Hz supply is

A. 150 Hz B. 25 Hz C. 100 Hz D. zero E. 50 Hz

1699. A photodiode used as a light detector is normally operated in

A. breakdown as a regulator B. zero bias only C. the saturation region of a transistor D. reverse bias E. forward bias

1700. A light emitting diode emits light when it is

A. cooled B. forward biased C. unbiased D. in breakdown E. reverse biased

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