(a) Define specific resistance. (b) What happens to the specific resistance of a conductor if its length is doubled? (c) Name a substance whose specific resistance remains almost unchanged with the increase in its temperature.

Choose the correct relation for e.m.f. (ε) and terminal voltage V: (a) ε = V [always] (b) V > ε [always] (c) V < ε [when the cell is in use] (d) None of these

When a current I flows through a wire of resistance R for time t then the electrical energy produced is given by: (a) I2Rt (b) IR2t (c) IRt (d) IRt2

‘A geyser is rated 240 W – 220 V’. Explain the meaning of this statement.

Three identical bulbs B1, B2 and B3, each of power rating 18 W, 12 V, are connected to a battery of 12 V as shown. (a) Calculate: (i) the resistance of each bulb (ii) the current drawn from the cell (b) If bulb B3 is removed from the circuit, will the brightness of bulb B1 increase, decrease or remain the same?

5 bulbs are connected in series in a room. One bulb is fused. It is removed and remaining 4 bulbs are again connected in series to the same circuit. What will be the effect on the following physical quantities? (Increases, Decreases, Remain Same) (a) Resistance (b) Intensity of light

The potential difference between the terminals of a cell in a closed circuit is called: (a) terminal voltage (b) electromotive force (c) voltage drop (d) none of these

The specific resistance of a wire depends on: (a) its length (b) the material of the wire (c) its cross-sectional area (d) its radius

Complete the following by choosing the correct answers from the bracket: (a) In uniform circular motion the centrifugal force acts ............... [towards the centre/away from the centre/along the tangential direction]. (b) Refractive index of a medium is independent of ............... [temperature/angle of incidence/wavelength of light]. (c) Heat absorbed during change of phase depends on ............... [mass/change in temperature/specific heat capacity] of the substance. (d) Emf of a cell is ............... [greater than/less than/equal to] the terminal voltage when the cell is in open circuit. (e) In a step-up transformer the turns ratio is ............... [more than 1/less than 1/equal to 1]. (f) The nuclear radiation with lowest ionising power is ............... [α/β/γ].

Study the diagram: (a) Calculate the total resistance of the circuit. (b) Calculate the current drawn from the cell. (c) State whether the current through 10 Ω resistor is greater than, less than or equal to the current through the 12 Ω resistor.

A current flows through a metallic conductor for a long period of time. State the change you would expect in its: (a) Resistance (b) Resistivity

In the given circuits Y and Z, the resistors, R₁ and R₂, are connected in : (a) series in both the circuits (b) parallel in both the circuits (c) parallel in Y and series in Z (d) series in Y and parallel in Z