Question

Q3/1/ Some copper wire has a resistance of 200 Ohm at 20.C.A current is passed through the wire and the temperature rises to 90°C. Determine the resistance of the wire at 90-C, assuming that the temperature coefficient of resistance * .is 0.004/-C at 0 C 251.85 Ohm O 201.666 Ohm 352.778 Ohm 232.232 Ohm 220 Ohm O 521.65 Ohm O

dc electric motor consumes 36 MJ when connected to a 250 V supply for 1 hour . Find the power rating of the motor * .and the current taken from the supply

Answer 1

3: R_{​​​​​​t}​= To(1+aplha(T2-T1))

200=Ro(1+.004×20)

Ro=185.185ohm

R at 90°C is 251.85ohm

4: power=energy/time= 36000000/3600=10kW

Current=power/voltage=40A

(3) Salution 2002 Roo Roo'c = ? Ry= Ro [1+ 2(T2-T.)] Rta) Gonductor Resistance at Temploratuve "T" Ro» (Releverpce temb) Resistance T2 - T1 =) Change in temp. da) Temp. coefficient of resistance. 200= Ro [1+ 0,004 X 20] 3) Ro=(-2 2.00 H0.08 > 185.1852. Now, Rgoo = 185.185 [1+ 0.004 X 900] 185.185 (1+.360) = 251.85 ohm (-2). R90o = 2.51.852 a Solution: Given, Power-? Energy 36 MJ = 36X10° Joules Time = Ihre 3600 seconds. Power: Energy - (36X106 10kW Time Current = ? ( Power = VI) >> Gurrent= 10000 = 40 Amperes CS 250 (36X000) = canned with CamScanner