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Showing 2201 to 2225 of 3046 questions (page 89 of 122).

2201. Light propagates along an optical fibre mainly by

A. refraction at the far end B. dispersion C. polarization D. total internal reflection E. diffraction

2202. The resolving power of a telescope increases when

A. the aperture is increased B. the magnification is reduced C. the focal length of the eyepiece is increased D. the aperture is decreased E. the wavelength is increased

2203. In a compound microscope, the objective forms an image that is

A. virtual and diminished B. real and diminished C. real, inverted and magnified D. virtual and erect E. at infinity

2204. The value of the universal gas constant R in SI units is

A. 0.083 B. 8.314 C. 0.0821 D. 62.4 E. 1.987

2205. The first law of thermodynamics is a statement of the conservation of

A. charge B. mass C. entropy D. energy E. momentum

2206. For an isothermal expansion of an ideal gas, the change in internal energy is

A. positive B. equal to the heat absorbed times gamma C. negative D. equal to the work done E. zero

2207. For one mole of an ideal gas, Cp - Cv equals

A. R B. R/2 C. gamma R D. 2R

2208. The efficiency of a Carnot engine operating between temperatures T1 (source) and T2 (sink) is

A. 1 - T2/T1 B. T2/T1 C. T1/T2 D. 1 - T1/T2 E. T1 - T2

2209. A Carnot engine works between 500 K and 300 K. Its efficiency is

A. 80% B. 30% C. 20% D. 40% E. 60%

2210. In an adiabatic process

A. temperature remains constant B. internal energy remains constant C. pressure remains constant D. volume remains constant E. no heat enters or leaves the system

2211. For any spontaneous natural process, the entropy of the universe

A. becomes zero B. decreases C. increases D. remains constant E. becomes negative

2212. The value of the Coulomb constant 1/(4 pi epsilon_0) in SI units is about

A. 9 x 10^9 B. 8.85 x 10^-12 C. 3 x 10^8 D. 1.6 x 10^-19 E. 6.63 x 10^-34

2213. The electric field intensity inside a hollow charged conductor in electrostatic equilibrium is

A. infinite B. zero C. maximum D. equal to the surface field E. uniform and non-zero

2214. The capacitance of a parallel plate capacitor with plate area A and separation d in vacuum is

A. d / epsilon_0 A B. epsilon_0 A d C. epsilon_0 A / d D. epsilon_0 d / A E. A d / epsilon_0

2215. Three capacitors of 3 microfarad each are connected in series. The equivalent capacitance is

A. 0.33 microfarad B. 3 microfarad C. 6 microfarad D. 9 microfarad E. 1 microfarad

2216. The energy stored in a capacitor of capacitance C charged to potential difference V is

A. CV B. C2V C. (1/2)CV D. (1/2)CV2 E. CV2

2217. Inserting a dielectric slab between the plates of a capacitor at constant charge

A. decreases the capacitance B. increases the electric field C. has no effect D. increases the capacitance E. increases the potential difference

2218. Gauss's law relates the electric flux through a closed surface to

A. the surface area B. the field at the surface only C. the volume enclosed D. the potential at the centre E. the charge enclosed

2219. Kirchhoff's first rule is based on the conservation of

A. flux B. charge C. momentum D. energy E. mass

2220. A Wheatstone bridge is balanced when

A. R1 R3 = R2 R4 B. R1 R2 = R3 R4 C. R1/R2 = R3/R4 D. the galvanometer reads maximum E. R1 + R2 = R3 + R4

2221. The resistance of a thermistor with a negative temperature coefficient

A. is independent of temperature B. varies linearly with current C. increases with temperature D. becomes zero at 0 K E. decreases with temperature

2222. Maximum power is delivered by a cell of emf E and internal resistance r to an external resistance R when

A. R = 2r B. R = 0 C. R = r D. R = r/2 E. R is infinite

2223. The specific resistance of a conductor depends on

A. its shape B. the nature of the material and temperature C. its area of cross section D. its length E. the current through it

2224. Two resistances of 6 ohm and 3 ohm are connected in parallel. The equivalent resistance is

A. 18 ohm B. 3 ohm C. 9 ohm D. 2 ohm E. 4.5 ohm

2225. The force on a charge q moving with velocity v at angle theta to a magnetic field B is

A. qvB sin theta B. qvB tan theta C. qvB cos theta D. qv/B E. qB/v

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