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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.
संबंधित प्रश्न
Why are metals good conductors of electricity whereas glass is a bad conductor of electricity? Give reason?
Three 2 V cells are connected in series and used as a battery in a circuit.
What is the p.d. at the terminals of the battery?
What is the unit of electric current?
A current of 4 A flows around a circuit for 10 s. How much charge flows past a point in the circuit in this time?
Write down the formula which relates electric charge, time and electric current
Why should the resistance of:
a voltmeter be very large?
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.
Following graph was plotted between V and I values:
What would be the values of `V/I` rations when the potential difference is 0.8 V, 1.2 V and 1.6 V respectively?
What conclusion do you draw from these values?
What is the resistance of the wire?
What happens to the other bulbs in a parallel circuit if one bulb blows off?
Draw a circuit diagram to show how two 4 V electric lamps can be lit brightly from two 2 V cells.
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.
(c) In which circuit, if one bulb blows out, all other will stop glowing?
How do you think the brightness of two lamps arranged in parallel compares with the brightness of two lamps arranged in series (both arrangements having one cell)?
In which of the following cases more electrical energy is consumed per hour?
(i) A current of 1 ampere passed through a resistance of 300 ohms.
(ii) A current of 2 amperes passed through a resistance of 100 ohms.
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.
Which effect of current is utilised in an electric light bulb?
Define the term resistivity.
A wire of uniform thickness with a resistance of 27Ω is cut into three equal pieces and they are joined in parallel. Find the equivalent resistance of the parallel combination.
Calculate the equivalent resistance between A and B in the adjacent diagram.
Electrical appliances have voltage and power ratings as listed below. Which
has the larger working resistance?
| Appliances | Voltage (V) | Power (W) |
| (a) Washing machine | 250 | 3000 |
| ( b) Television | 240 | 160 |
| (c)240 | 240 | 1500 |
| ( d) Hair curler | 250 | 20 |
| ( e) Car head lamp | 12 | 36 |
Tick (✓) the correct choice among the following :
(a) A strong short bar magnet is dropped into a solenoid connected to a
galvanometer as shown in fig . The galvanometer shows a deflection to the left when the current in the coil as seen from above is counter clockwise. Which one of the following shows the correct deflection of the galvanometer when the magnet is at posi tions A, Band C.
Tick (✓) the correct choice among the following :
In fig .XY is at right angles to the magnetic field. The direction in
which XY should be moved to induce an electron flow in the direction Y to X as indicated by the arrow is
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.
True or False – If False give the correct answer
The representation of the electric current is A
When an electric current is passed, electrons move from:
Assertion (A): Electric current will not flow between two charged bodies when connected if their charges are the same.
Reason (R): Current is the rate of flow of charge.
A charge of 400C flows through a conductor for 13 minutes and 20 seconds. Find the magnitude of the current flowing through the conductor.
