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प्रश्न
What is an electric current?
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उत्तर
An electric current is the flow of electric charge called electrons in a conductor and its magnitude is the amount of electric charge passing through a given point of the conductor in one second.
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संबंधित प्रश्न
Calculate the number of electrons constituting one coulomb of charge.
By what name is the physical quantity coulomb/second called?
What is the unit of electric current?
What Makes an Electric Current Flow in a Wire?
Why should the resistance of:
an ammeter be very small?
One coulomb of charge flows through any cross-section of a conductor in 1 second. What is the current flowing through the conductor?
A student made an electric circuit shown here to measure the current through two lamps.
Are the lamps in series or parallel?
(a) Are the lamps in series or parallel?
(b) The student has made a mistake in this circuit. What is the mistake?
(c) Draw a circuit diagram to show the correct way to connect the circuit. Use the proper circuit symbols in your diagram.
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 following table shows the current in Amperes and potential differences in Volts.
- Find the average resistance.
- What will be the nature of the graph between the current and potential difference? (Do not draw a graph.)
- Which law will the graph prove? Explain the law.
| V (volts) | I (amp) |
| 4 | 9 |
| 5 | 11.25 |
| 6 | 13.5 |
Complete the following sentence:
A fuse is a short piece of wire of high ......... and low
Two resistors P and Q of the same material and length but of different thickness are connected in parallel to a battery. The cross- sectional area of P is twice that of Q. What is the ratio of
(a) The resistance of P to the resistance of Q?
(b) The current in P to the current in Q?
Complete the following table. The first answer has been given as an example
| Quantity | Unit |
|
(a) Electrical potential Volt ( b) Resistance ( c) Power ( d) Energy ( e) Resistivity |
Volt ........ .......... ............ .............. |
Name the principle on which a transformer works.
An electric bulb is rated at 220 V, 100 W.
- What is its resistance?
- What safe current can be passed through it?
Three heaters each rated 250 W, 100 V are connected in parallel to a 100 V supply. Calculate :
The total current taken from the supply
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.
State whether the following statement is True or False:
The SI unit of charge is the coulomb.
Two electric bulbs rated 100 W; 220 V and 60 W; 220 V are connected in parallel to electric mains of 220 V. Find the current drawn by the bulbs from the mains.
The flow of electric charge per unit time is called potential difference.
