Advertisements
Advertisements
Question
How does the resistance of a wire depend on its radius? Explain your answer.
Advertisements
Solution
Resistance of a wire is inversely proportional to the area of cross-section of the wire.
`R ∝ 1/"r"^2 or R prop 1/"a" or R ∝ 1/"𝜋𝑟"^2`
where 'a' is the area of cross-section and r is the radius of wire and R is the resistance. In other words thick wire offers less resistance and thin wire offers more resistance. In thick conductor electrons suffer less collisions.
APPEARS IN
RELATED QUESTIONS
Two copper wires are of the same length, but one is thicker than the other. Which wire will have more resistance?
Assertion (A): Copper is used to make electric wires.
Reason (R): Copper has very low electrical resistance.
Exercise.
The values of current (I) flowing through a resistor for various potential differences V across the resistor are given below. What is the value of resistor?
| I (ampere) | 0.5 | 1.0 | 2.0 | 3.0 | 4.0 |
| V (volt) | 1.6 | 3.4 | 6.7 | 10.2 | 13.2 |
The effective resistance of three resistors connected in series is lesser than the lowest of the individual resistances.
An electric bulb is rated ‘240 V, 100 W’.
- What information can you get from the above statement?
- What will happen if this bulb is connected across 220 V?
- Calculate the resistance of the bulb.
- Also find the energy consumed by the bulb in 10 minutes.
What is resistance?
Two conductors of resistance 2 R and R are connected in series in a battery circuit. The ratio of heat developed In them is ______.
The resistance of a conductor is R. If Its length is doubled, then its new resistance will be ______.
If the area of cross-section of the conductor is doubled its resistance gets ______.
Three resistors are connected in series with a cell. If the current in each resistor is 1.5A, then the current through the cell will be ______.
