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प्रश्न
Define an electric current.
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उत्तर १
An electric current is measured by the amount of electric charge moving per unit time at any point in the circuit.
उत्तर २
The magnitude of an electric current is the number of electric charges flowing through a conductor in one second.
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संबंधित प्रश्न
What does an electric circuit mean?
Draw the electrical symbols of the following components and state its use:
Ammeter.
Which statement/statement is/are correct?
1. An ammeter is connected in series in a circuit and a voltmeter is connected in parallel.
2. An ammeter has a high resistance.
3. A voltmeter has a low resistance.
(a) 1, 2, 3
(b) 1, 2
(c) 2, 3
(d) 1
An electric circuit consisting of a 0.5 m long nichrome wire XY, an ammeter, a voltmeter, four cells of 1.5 V each and a plug key was set up.
(i) Draw a diagram of this electric circuit to study the relation between the potential difference maintained between the points 'X' and 'Y' and the electric current flowing through XY.
The circuit diagram given below shows the combination of three resistors R1, R2 and R3:
Find :
(i) total resistance of the circuit.
(ii) total current flowing in the circuit.
(iii) the potential difference across R1.
A p.d. of 6 V is applied to two resistors of 3 Ω and 6 Ω connected in parallel. Calculate:
(a) the combined resistance
(b) the current flowing in the main circuit
(c) the current flowing in the 3 Ω resistor.
Ten bulbs are connected in a series circuit to a power supply line. Ten identical bulbs are connected in a parallel circuit to an identical power supply line.
(b) In which circuit, if one bulbs be brighter?
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
Two lamps, one rated 40 W at 220 V and the other 60 W at 220 V, are connected in parallel to the electric supply at 220 V.
(a) Draw a circuit diagram to show the connections.
(b) Calculate the current drawn from the electric supply.
(c) Calculate the total energy consumed by the two lamps together when they operate for one hour.
An electric bulb is rated as 10 W, 220 V. How many of these bulbs can be connected in parallel across the two wires of 220 V supply line if the maximum current which can be drawn is 5 A?
A cell supplies a current of 1.2 A through two 2 Ω resistors connected in parallel. When the resistors are connected in series, it supplies a current of 0.4 A. Calculate:
(i) the internal resistance and (ii) e.m.f. of the cell.
Draw a schematic diagram of an electric circuit consisting of a battery of two cells each of 1.5 V, 5 Ω, 10 Ω and 15 Ω resistors and a plug key, all connected in series.
Tick(✓) the correct choice in the following:
24 watt, 12 volt head lamp is fully lit by connecting it to a 12 volt
battery. The working resistance of the lamp is
Find the effective resistance in the following circuit diagrams (Fig.):
The circuit diagram (Fig.) shows a battery of e.m.f. 6 volts and internal
resistance of 0.8 Ω oonnected in series. Find the
(a) Current reoorded by the ammeter,
(b) P.d. across the terminals of the resistor B,
( c) Current passing through each of the resistors B, C and D, and
( d) P.d. across the terminals of the battery.
The following appliances are to be used on 240 V supply. Calculate the current used by each and say which fuse, 2 amp, 5 amp or 13 amp should be incorporated with each, (i) A television rated at 150 W, (ii) An electric iron rated at 750 W, (iii) An immersion heater rated at 3000 W, (iv) A hair dryer rated at 500 W. How much will it cost to run the television set for 100 days for an average of 4 hours a day at 60 paise per unit?
A 3 pin mains plug is fitted to the lead for a 1 kW electric kettle to be used on a 250 V A.C. supply. Which of the following statements is NOT correct?
(a) A 13 A fuse is the most appropriate value to use.
(b) The brown wire should be connected to the live side of the mains.
Calculate the current through a 60 W lamp rated 250 V. If the line voltage falls to 200 V, how is power consumed by the bulb affected?
An electric bulb is rated at 220 V, 100 W.
- What is its resistance?
- What safe current can be passed through it?
A bulb is connected to a battery of p.d. 4 V and internal resistance 2.5 Ω . A steady current of 0.5 A flows through the circuit. Calculate:
The energy dissipated in the bulb in 10 minutes.
My mother was operating washing machine on Sunday morning. Suddenly, she saw a spark coming out of the electric board and the electric current in the house failed. An electrician was called to look into the matter. What should he have noticed.
Answer the following question.
An electric lamp of resistance 20 Ω and a conductor of resistance 4 0 are connected to a 6 V battery as shown in the circuit. Calculate: 
(a) the total resistance of the circuit,
(b) the current through the circuit,
(c) the potential difference across the (i) electric lamp and (ii) conductor, and
(d) power of the lamp.
What is the speed of electric current?
Name any two devices, which are working on the heating effect of the electric current.
What is the rate at which charges flow past a point on a circuit?
