Current Electricity — Physics STD 12 Science — Question

A triode whose mutual conductance is 2.5 m A/volt and anode resistance is 20 kilo ohm, is used as an amplifier whose amplification is 10. The resistance connected in plate circuit will be(a) 1 kW  (b) 5 kW(c) 10 kW(d) 20 kW

A copper voltameter is connected in series with a heater coil of resistance 0.1 Ω. A steady current flows in the circuit for twenty minutes and mass of 0.99 g of copper is deposited at the cathode. If electrochemical equivalent of copper is 0.00033 gm/C, then heat generated in the coil is(a) 750 J  (b) 650 J(c) 350 J  (d) 250 J

Find the true statement.

The maximum magnification that can be obtained with a convex lens of focal length 2.5 cm is (the least distance of distinct vision is 25 cm) (a) 10(b) 0.1(c) 62.5(d) 11

The error in measuring the current with a tangent galvanometer is minimum when the deflection is about

The axis of rotation of a purely rotating body:

1. Must pass through the centre of mass.
2. May pass through the centre of mass.
3. Must pass through a particle of the body.
4. May pass through a particle of the body.

Which of the following spectral series in hydrogen atom give spectral line of 4860 Å (a) Lyman(b) Balmer(c) Paschen(d) Brackett

When the number of nucleons in a nucleus increases, the binding energy per nucleon:

A combination of two thin convex lenses of focal length 0.3 m and 0.1 m will have minimum spherical and chromatic aberrations if the distance between them is(a) 0.1 m(b) 0.2 m(c) 0.3 m (d) 0.4 m