Same chapter3 marksDifficulty: Medium
Why are the connecting wires in a circuit made thick and short, while the element of a heater is made long and thin?
Current Electricity
3 marksDifficulty: Medium
On what factors does the resistance of a wire depend, and how?
Original Khojo Papers practice question — not from a past board paper.
Answer
The resistance is directly proportional to the length of the wire and inversely proportional to its area of cross-section, and it depends on the material through its resistivity. For most metals it also rises as the temperature rises.
No citable source has been recorded for this record. Treat it as practice material, not as fact.
Explanation
This is summarised as R = ρl/A.
Related questions
From the same topic and chapter, at a similar level.
Same chapter3 marksDifficulty: Medium
An electric bulb is marked 100 W, 220 V. Calculate the current it draws and its resistance in normal use.
Current Electricity
Same chapter3 marksDifficulty: Medium
Three resistors of 2 Ω, 3 Ω and 5 Ω are joined in series across a 20 V supply. Calculate the current in the circuit and the potential difference across the 3 Ω resistor.
Current Electricity
Same chapter3 marksDifficulty: Medium
An appliance of power 1.5 kW is used for 4 hours a day for 30 days. Calculate the energy consumed in kilowatt hours.
Current Electricity
Same chapter3 marksDifficulty: Medium
Two resistors of 6 Ω each are connected in parallel. Calculate the equivalent resistance.
Current Electricity
Same chapter3 marksDifficulty: Medium
Why are the lamps in a house wired in parallel and not in series?
Current Electricity