Advertisements
Advertisements
प्रश्न
A bulb marked 12 V, 24 W operates on a 12 V battery for 20 minutes. Calculate:
- The current flowing through it, and
- The energy consumed.
Advertisements
उत्तर
Given Power, P = 24 W
Voltage, V = 12 V
Current, I = ?
As power, P = VI
- I = `24/12
= 2 "A"` - Energy, E = P × t
E = 24 × 20 × 60 sec
E = 28800 J
APPEARS IN
संबंधित प्रश्न
What actually travels through the wires when you switch on a light?
Why should the resistance of:
an ammeter be very small?
In the circuit shown below, the voltmeter reads 10 V.
(a) What is the combined resistance?
(b) What current flows?
(c) What is the p.d. across 2 Ω resistor?
(d) What is the p.d. across 3 Ω resistor?
The lamps in a house hold circuit are connected in parallel because:
(a) this way they required less current
(b) if one lamp fails the others remain lit
(c) this way they require less power
(d) if one lamp fails the other also fail
A wire of length 5 m has a resistance of 2.0 Ω calculate:
(a) the resistance of wire of length 1 m
(b) the equivalent resistance if two such wires each of length 2 m are joined in parallel.
(c) the resistance of 1 m length of wire of same material but of half diameter.
60 joules of heat was dissipated in a resistor when 20 C flowed for 5 s. Calculate:
(a) P.d. across the resistor,
(b) Resistance of the resistor, and
(c) Average power dissipated in the resistor.
An electric bulb is rated at 220 V, 100 W.
- What is its resistance?
- What safe current can be passed through it?
A battery of e.m.f. 15 V and internal resistance 2 Ω is connected to two resistors of resistances 4 ohm and 6 ohm joined (a) in series. Find in each case the electrical energy spent per minute in 6 Ω resistor.
A geyser is rated 1500 W, 250 V. This geyser is connected to 250 V mains. Calculate:
- The current drawn,
- The energy consumed in 50 hours, and
- The cost of energy consumed at ₹ 4.20 per kWh.
Three resistances, of which two are equal when connected in series have an effective resistance of 30 ohms. When the three resistances are connected in parallel, the effective resistances is 3 ohms. Find the values of the individual resistances.
