The resistance of hot tungsten filament is about 10 times the cold resistance. What will be the resistance of 100 W and 200 V lamp when not in use?
20 Ω
40 Ω
200Ω
400Ω
Iron and silicon wires are heated from 30°C to 50°C.The correct statement is that
resistance of both the wires increases
resistance of both the wires decreases
resistance of iron wire increases and that of silicon wire decreases
resistance of iron wire decreases and that of silicon wire increases
A 2 kW boiler used for 1 hour everyday consumes electrical energy in thirty days equal to
120 units
60 units
15 units
30 units
A storage battery is connected to the mains for charging with emf of 12.5 V. The internal resistance of the storage battery is 1 Ω. When the charging current is 0.5 A, the potential difference across the storage battery is
13 V
12.5 V
12 V
11.5 V
n equal resistors are first connected in series and then connected in parallel. What is the ratio of the maximum to the minimum resistance ?
n
1/n2
n2
1/n
A 10 metre potentionmeter wire has a resistance of 20 Ω. It is connected in series with a battery of emf 2.5 volt and a resistance of 5 Ω. The potential gradient along wire in volt cm-1 is
0.002
0.02
0.2
0.0025
The negative Zn pole of a Daniell cell, sending a contant current through a circuit, decreases in mass by 0.13 g in 30 minutes. If the electrochemical equivalent of Zn and Cu are 32.5 and 31.5 respectively, the increase in the mass of the positive Cu pole in this time is
0.180 g
0.141 g
0.126 g
0.242 g
A 220 volt, 1000 watt bulb is connected across a 110 volt mains supply. The power consumed will be
750 watt
500 watt
250 watt
1000 watt
The resistance of a discharge tube is
zero
ohmic
non - ohmic
infinity
Four bulbs marked 40 W, 250 V are connected in series with 250 V mains, the total power consumed is
10 W
40 W
320 W
160 W
