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Showing 2651 to 2675 of 3046 questions (page 107 of 122).

2651. Two electric field lines can never intersect because

A. the field would be zero there B. the field would have two directions at one point C. the lines are imaginary D. charges repel E. the field is conservative

2652. The force between two charges of 1 coulomb each placed 1 metre apart in vacuum is

A. 8.85 x 10^-12 N B. 1.6 x 10^-19 N C. 9 x 10^9 N D. 1 N E. 9 x 10^-9 N

2653. For capacitors connected in series, the quantity that is the same on each is the

A. potential difference B. stored energy C. dielectric constant D. capacitance E. charge

2654. The relation between electric field intensity and potential is

A. E = V/r2 B. V = E r2 C. E = V r D. E = -dV/dr E. E = dV/dr times r2

2655. Two resistors of 4 ohm and 6 ohm are joined in series across a 20 V supply. The current is

A. 1.2 A B. 0.5 A C. 2 A D. 10 A E. 5 A

2656. An ideal ammeter and an ideal voltmeter have respectively

A. equal finite resistances B. zero and infinite resistance C. zero and zero resistance D. infinite and infinite resistance E. infinite and zero resistance

2657. A galvanometer is converted into an ammeter by connecting

A. a capacitor in series B. an inductor in series C. a high resistance in series D. a diode in parallel E. a low resistance in parallel

2658. The heat produced in a resistor is given by

A. I2Rt B. I2R/t C. IRt2 D. IR2t E. IRt

2659. The resistance of a conductor of length L, area of cross section A and resistivity rho is

A. L / rho A B. rho A / L C. A / rho L D. rho L / A E. rho L A

2660. In the resistor colour code, the fourth band indicates

A. the temperature coefficient B. the multiplier C. the first digit D. the tolerance E. the power rating

2661. The magnetic field at a perpendicular distance r from a long straight wire carrying current I is

A. 2 pi mu_0 I r B. mu_0 I / (2 pi r) C. mu_0 I / (2r) D. mu_0 I / r2 E. mu_0 I r

2662. The force on a 2 m length of wire carrying 3 A placed perpendicular to a 0.5 T field is

A. 12 N B. 0.75 N C. 3 N D. 1.5 N E. 6 N

2663. A loudspeaker converts electrical energy into sound using

A. piezoelectric heating only B. the photoelectric effect C. electrostatic attraction D. thermal expansion E. the force on a current carrying coil in a magnetic field

2664. A diamagnetic substance in a magnetic field is

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

2665. Flux linkage through a coil of N turns each enclosing flux Phi is

A. Phi/N B. N Phi C. Phi D. N2 Phi E. N/Phi

2666. A generator converts

A. light to electrical energy B. heat to electrical energy C. chemical to electrical energy D. mechanical energy to electrical energy E. electrical energy to mechanical energy

2667. Self induction in a coil always

A. opposes the change in current B. assists the change in current C. reverses the current D. increases the resistance E. stops the current

2668. A transformer with 500 primary turns and 2500 secondary turns supplying 220 V to the primary gives a secondary voltage of

A. 44 V B. 550 V C. 220 V D. 2500 V E. 1100 V

2669. The peak to peak value of an alternating voltage of peak value V0 is

A. V0/sqrt(2) B. V0/2 C. V0 D. 2V0 E. V0 sqrt(2)

2670. A radio receiver is tuned to a station by adjusting the

A. capacitance of the tuning circuit B. supply voltage C. aerial length only D. loudspeaker impedance E. resistance in the circuit

2671. Electrical power is transmitted at high voltage over long distances in order to

A. avoid using transformers B. reduce the voltage at the consumer end directly C. increase the current D. increase the resistance of the line E. reduce the current and hence the I squared R loss

2672. The bulk modulus of a material relates

A. shear stress to shear strain B. tensile stress to longitudinal strain C. volume stress to volume strain D. strain to time E. stress to temperature

2673. A material that can be drawn into thin wires is described as

A. ductile B. amorphous C. elastic only D. malleable E. brittle

2674. Doping a semiconductor with a trivalent impurity produces

A. an intrinsic semiconductor B. a conductor C. an insulator D. a p-type semiconductor E. an n-type semiconductor

2675. In a metallic conductor, the valence and conduction bands

A. have a gap of 1.1 eV B. overlap or the valence band is partly filled C. are widely separated D. are both completely empty E. are both completely full

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