Calculate the potential difference required across a conductor of resistance 5 Ω to make a current of 1.5 A flow through it.
A torch bulb has 1 Ω resistance. It draws a current of 0.3 A when glowing from a source of 3 V. calculate the resistance of the bulb when glowing and explain the reason for the difference in resistance.
How much current does an electric heater draw from a 220 V line, if the resistance of the heater (when hot) is 50 Ω?
How much work is done in moving a charge of 2 C across two points having a potential difference of 12 V?
An incandescent lamp of resistance 80 Ω draws a current of 0.75 A. Find the line voltage.
The resistance of a wire of length 80 cm and of uniform area of cross-section 0.025 cm2, is found to be 1.50 ohm. Calculate the resistivity of the wire.
Calculate the resistance of 1 km long copper wire of radius 1 mm. Resistivity of copper is 1.72 × 10–8 Ω m.
Two copper wires A and B of length 30 m and 10 m have radii 2 cm and 1 cm respectively. Compare the resistances of the two wires. Which will have less resistance?
A 4 Ω wire is doubled on it. Calculate the new resistance of the wire.
What should be the length of a nichrome wire of resistance 4.5Ω, if the length of a similar wire is 60 cm and resistance 2.5Ω?
Resistance of a metal wire of length 1 m is 26 Ω at 20°C. If the diameter of the wire is 0.3 mm, what will be the resistivity of the metal at that temperature?
Suppose a 6-volt battery is connected across a lamp whose resistance is 20 Ω through a variable resistor as shown in the figure. If the current in the circuit is 0.25 A, calculate the value of the resistance from the resistor which must be used?
In the circuit diagram given in fig. (a), suppose the resistors R1, R2 and R3 have values 5 Ω, 10 Ω and 30 Ω respectively, which have been connected to a battery of 12 V. calculate (a) the current through each resistor, (b) the total current in the circuit, and (c) the total circuit resistance.
