# Electricity Worksheet-19

Electricity Worksheet-19

1. An electric bulb draws 1.2 A current at 6.0 V. Find the resistance of the bulb.

1. Which will have a higher resistivity: a conductor or an insulator ?

1. Two wires of same material and same length have radii r1 and r2 respectively. Compare their resistances.

1. Name a substance whose resistance decreases with temperature.

1. Name a substance whose resistance almost remains unchanged by increase of temperature.

1. Distinguish between kilowatt and kilowatt hour.

1. Name two special characteristics of a heater coil.

1. A 60 W bulb carries a current 0.5 A. Find the charge that passes through it in 2 hour.

1. Calculate the current through a lamp of 25 W operating at 200 V.

1. Under what conditions is Ohm's law applicable?

1. An insulator

1. If R1 and R2 are resistances of the two wires,

1. Germanium which is a semiconductor.

1. Manganin which is an alloy of Cu, Ni and Mn.

1. A kilowatt (kW) is a unit of power and a kilowatt hour (kWh) is a unit of electric energy.

1kWh = 1 kW × 1h.

1. A heater coil should have (i) high resistivity and (li) high melting point.

1. Q = It = 0.5 × (2 × 60 × 60)

= 3600 C.

1. If the physical conditions like temperature, etc., of a conductor do not change when current is passed through it.