Page 254 - Basic Electrical Engineering

35. Derive the formula used in calculating the temperature coefficient of resistance at any
temperature from its given value at any particular temperature.

B. Numerical Problems

36. A long copper wire has a resistance of 25 Ω at 40°C. Its resistance becomes 45 Ω when the
temperature is 100°C. Calculate the value of its resistance at 0°C.

[Ans 11.7 Ω]

37. At what value of load resistance R , maximum power will be transferred in the circuit shown.
L

Figure 2.167

38. Calculate the value of R for which maximum power will be transferred from the source to the load
L
in the network shown. Also calculate the value of maximum power transferred.

Figure 2.168

[Ans R = 7.33 Ω, P max = 0.545 W]
L

39. Apply Norton’s theorem to calculate the current through the 5 Ω resistor in the circuit shown. Also
verify by applying Thevenin’s theorem.