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Question
The resistance of a 1 m long nichrome wire is 6 ohm. If we reduce the length of the wire to 70 cm. what will its resistance be?
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Solution
Given, L1 = 1 m, R1 = 6 Ω, L2 = 70 cm = 0.7 m, R2 = ?
R = `rho L/A`
`therefore R_1 = rho L_1/A and R_2 = rho L_2/A`
`therefore R_2/R_1 = L_2/L_1 = 0.7/1` = 0.7
∴ R2 = 0.7, R1 = 0.7 × 6 = 4.2 Ω
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RELATED QUESTIONS
Three resistances x1, x2, and x3 are connected in a circuit in different ways. x is the effective resistance. The properties observed for these different ways of connecting x1, x2 and x3 are given below. Write the way in which they are connected in each case. (I-current, V-potential difference, x-effective resistance)
- Current I flows through x1, x2 and x3
- x is larger than x1, x2 and x3
- x is smaller than x1, x2 and x3
- The potential difference across x1, x2 and x3 is the same
- x = x1 + x2 + x3
- x = `1/(1/X_1 + 1/X_2 + 1/X_3)`
When two resistors are connected in series, their effective resistance is 80 Ω. When they are connected in parallel, their effective resistance is 20 Ω. What are the values of the two resistances?
