Advertisements
Advertisements
Question
A wire of resistance 3 ohm and length 10 cm is stretched to length 30 cm. Assuming that it has a uniform cross section, what will be its new resistance?
Advertisements
Solution
Because three times the original length of the wire 10 cm is stretched to 30 cm
∴ Resistance becomes 9 times its resistance, i.e. 3 × 9 = 27 Ω
`"R"_1 = ρ 30/(a/3)`
= `9 [ρ 10/a]` ...(i)
`"R"_2 = ρ 10/a` put in (i)
R1 = 9R
= 9 × 3
= 27 Ω
∴ R = 3 Ω
APPEARS IN
RELATED QUESTIONS
What will be the change in the current if the potential difference is kept constant and the resistance of the circuit is made four times?
- It will remain unchanged.
- It will become four times.
- It will become one-fourth.
- It will become half.
Write the SI unit of resistivity
Ohm's law gives a relationship between:
(a) current and resistance
(b) resistance and potential difference
(c) potential difference and electric charge
(d) current and potential difference
The graph between V and I for a conductor is a straight line passing through the origin.
Which law is illustrated by such a graph?
The resistors R1, R2, R3 and R4 in the figure given below are all equal in value.
What would you expect the voltmeter A, B and C to read assuming that the connecting wires in the circuit have negligible resistance?
Four resistances of 16 ohms each are connected in parallel. Four such combinations are connected in series. What is the total resistance?
Rewrite the following statement by selecting the correct option.
The S.I. unit of resistance is __________.
State the limitations of Ohm’s law.
State Ohm’s law? How can it be verified experimentally? Does it hold good under all conditions? Comment.
