Wave Optics — Physics STD 12 Science — Question

Which of the following of a radioactive material is a measure of its instability?

Kirchoffs law of junctions is also called the law of conservation of:

Let E, G and N represent the magnitudes of electromagnetic gravitational and nuclear forces between two electrons at a given separation. Then:

1. N > E > G
2. E > N > G
3. G > N > E
4. E > G > N

Which one of the series of hydrogen spectrum is in the visible region

(a) Lyman series

(b) Balmer series

(c) Paschen series

(d) Bracket series

Three unequal resistors in parallel are equivalent to a resistance 1 ohm.  If two of them are in the ratio 1 : 2 and if no resistance value is fractional, the largest of the three resistances in ohms is

(a) 4

(b) 6

(c) 8

(d) 12

What is the current in the circuit shown below

(a) 0 amp

(b)  amp

(c) 1 amp

(d) 0.10 amp

Gauss is unit of which quantity

(a) H

(b) B

(c) ∅

(d) I

The current in a triode at anode potential 100 V and grid potential – 1.2 V is 7.5 mA. If grid potential is changed to – 2.2 V, the current becomes 5.5 mA. the value of trans conductance (g_m) will be

(a) 2 mili mho

(b) 3 mili mho

(c) 4 mili mho

(d) 0.2 mili mho

A potentiometer consists of a wire of length 4 m and resistance 10Ω. It is connected to a cell of e.m.f. 2 V. The potential difference per unit length of the wire will be

(a) 0.5 V/m

(b)  2 V/m

(c)  5 V/m

(d) 10 V/m

Which of the following devices can be used as a square law device for modulation.