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Showing 551 to 575 of 3046 questions (page 23 of 122).

551. The intensity level of sound is measured in decibels on a scale that is

A. linear B. logarithmic C. exponential D. quadratic E. inverse square

552. Dark fringes in a two slit interference pattern occur where the path difference is

A. n lambda B. (n + 1/2) lambda C. n lambda / 2 D. 2 n lambda E. zero only

553. The colours seen in a thin film of oil on water are due to

A. dispersion B. interference of light reflected from the two surfaces C. total internal reflection D. polarization E. scattering

554. A wavefront is a surface on which all points have

A. the same amplitude B. the same phase C. the same wavelength only D. zero displacement E. maximum intensity

555. According to Huygens' principle, each point on a wavefront acts as

A. an absorber B. a source of secondary spherical wavelets C. a mirror D. a polarizer E. a node

556. In Young's experiment, if the separation between the slits is increased, the fringe spacing

A. increases B. decreases C. remains the same D. becomes zero immediately E. doubles

557. The angular magnification of an astronomical telescope in normal adjustment is

A. fe/fo B. fo/fe C. fo x fe D. 1 + fo/fe E. fo - fe

558. The defect of vision in which a person cannot see distant objects clearly is corrected using

A. a convex lens B. a concave lens C. a cylindrical lens D. a bifocal lens E. a plane mirror

559. An endoscope used in medicine works on the principle of

A. diffraction B. total internal reflection through optical fibres C. polarization D. interference E. dispersion

560. The value of the Boltzmann constant is about

A. 1.38 x 10^-23 J K-1 B. 8.314 J K-1 C. 6.63 x 10^-34 J s D. 1.6 x 10^-19 J E. 9.1 x 10^-31 J K-1

561. The work done by a gas expanding at constant pressure is

A. zero B. P times the change in volume C. V times the change in pressure D. nRT ln(V2/V1) E. (1/2)P V

562. In an isochoric process, the work done by the gas is

A. P delta V B. zero C. nRT D. equal to the heat supplied E. negative

563. The triple point of water is

A. 273.16 K B. 273.15 K C. 100 K D. 373.15 K E. 0 K

564. A heat engine cannot have an efficiency of 100 per cent because

A. friction is unavoidable in practice only B. some heat must always be rejected to the sink C. the first law forbids it D. the working substance has mass E. fuel is limited

565. The force between two charges placed in a medium of relative permittivity 4 compared with that in vacuum becomes

A. four times B. half C. one quarter D. unchanged E. twice

566. The electric potential at distance r from a point charge q is

A. kq/r2 B. kq/r C. kqr D. kq r2 E. kr/q

567. One electron volt is equal to

A. 1.6 x 10^-19 J B. 1.6 x 10^19 J C. 9.1 x 10^-31 J D. 6.63 x 10^-34 J E. 1 J

568. The charge stored on a 2 microfarad capacitor charged to 100 V is

A. 2 x 10^-4 C B. 2 x 10^-6 C C. 2 x 10^-2 C D. 200 C E. 2 C

569. Three capacitors of 2 microfarad each are connected in parallel. The equivalent capacitance is

A. 0.67 microfarad B. 2 microfarad C. 6 microfarad D. 8 microfarad E. 4 microfarad

570. The electric field between two large parallel plates carrying equal and opposite charges is

A. zero B. uniform C. proportional to the distance from a plate D. inversely proportional to the separation squared E. radial

571. The work done in moving a charge along an equipotential surface is

A. maximum B. zero C. negative D. equal to qV E. infinite

572. One ampere is equivalent to

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

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

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

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

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

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

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

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