Question

Q. An alternating voltage source of variable angular frequency ‘w’ and fixed amplitude ‘V’ is connected in series with a capacitance C and electric bulb of resistance R(inductance zero). When ‘w’ is increased-(i) The bulb glows dimmer.(ii) The bulb glows brighter.(iii) Net impedance of the circuit remains unchanged.(iv) Total impedance of the circuit increases. Answer: […]

Q. Which among the following, is not a cause for power loss in a transformer-(i) Eddy currents are produced in the soft iron core of a transformer.(ii) Electric Flux sharing is not properly done in primary and secondary coils.(iii) Humming sound produed in the tranformers due to magnetostriction.(iv) Primary coil is made up of a

Q. Two parallel plate capacitors X and Y, have the same area of plates and same separation between plates. X has air and Y with dielectric of constant 2 , between its plates. They are connected in series to a battery of 12 V. The ratio of electrostatic energy stored in X and Y is-(i)

Q. Three Charges 2q, -q and -q lie at vertices of a triangle. The value of E and V at centroid of triangle will be-(i) E#0 and V#0(ii) E=0 and V=0(iii) E#0 and V=0(iv) E=0 and V#0 Answer: (iii) E#0 and V=0 Superposition of Electric field -The resultant electric field at any point is equal

Q. Consider an uncharged conducting sphere. A positive point charge is placed outside the sphere. The net charge on the sphere is then,(i) negative and uniformly distributed over the surface of sphere(ii) positive and uniformly distributed over the surface of sphere(iii) negative and appears at a point the surface of sphere closest to point charge.(iv)

Q. Two parallel large thin metal sheets have equal surface densities 26.4×10-12 C/m2 of opposite signs. The electric field between these sheets is-(i) 1.5N/C(ii) 1.5 x 10-16 N/C(iii) 3 x 10-10N/C(iv) 3N/C Answer: (iv) 3N/C

Q. A cylinder of radius r and length l is placed in an uniform electric field parallel to the axis of the cylinder. The total flux for the surface of the cylinder is given by-(i) zero(ii) π r2(iii) E π r2(iv) )2 Eπ r2 Answer: (i) zero

Q. The instantaneous values of emf and the current in a series ac circuit are-E = Eo Sin ωt and I= Io sin( ωt+π/3) respectively, then it is(i) Necessarily a RL circuit(ii) Necessarily a RC circuit(iii)Necessarily a LCR circuit(iv) Can be RC or LCR circuit Answer: (iv) Can be RC or LCR circuit E =

Q. A 20 volt AC is applied to a circuit consisting of a resistance and a coil with negligible resistance. If the voltage across the resistance is 12 volt, the voltage across the coil is-(i) 16 V(ii) 10 V(iii) 8 V(iv) 6 V Answer: (i) 16 V

Q. Which of the following graphs represent the variation of current(I) with frequency (f) in an AC circuit containing a pure capacitor? Answer: Correct option is (iii)