Advertisements
Advertisements
Question
A current of 1 A is drawn by a filament of an electric bulb. Number of electrons passing through a cross section of the filament in 16 seconds would be roughly
Options
1020
1016
1018
1023
Advertisements
Solution
1020
Explanation -
Current, i = 1A
Time, t = 16s
`"i" = "q"/"t"`
`"q" = "i" xx "t"`
q = 1 × 16
q = 16 C
Now,
q = n × e
where, n is number of electrons lost or gained
e = charge on 1 electron (1.6 × 10-19 C)
`"n" = "q"/"e"`
`n = 16/(1.6 xx 10^(-19))`
n = 1020
APPEARS IN
RELATED QUESTIONS
Define the unit of current.
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?
The atoms of copper contain electrons and the atoms of rubber also contain electrons. Then why does copper conduct electricity but rubber does not conduct electricity?
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
A battery of 9 V is connected in series with resistors of 0.2 Ω, 0.3 Ω, 0.4 Ω, 0.5 Ω and 0.12 Ω. How much current would flow through the 12 Ω resistor?
Define the term resistivity.
A 720 W heater operates from a 220 V line voltage. Calculate:
(a) The electrical energy consumed by the heater in 3 h.
(b) The cost of electrical energy consumption at the rate of 60 paise per kWh.
Complete the following sentence:
Fuse wire has a ............ Melting point and it is made of an alloy of ......... and if the current in a circuit rises too high, the fuse wire ...........
Two resistors of 4 Ω and 6 Ω are connected in parallel. The combination is
connected across a 6 volt battery of negligible resistance. Calculate:
( i) The power supplied by the battery,
(ii) The power dissipated in each resistor.
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.
A wire is passed through a piece of cardboard as shown in fig .. An electric current flows vertically down the wire and then flows back up. The two sections of the write are observed to repel each other.
(a) Wi th the aid of a diagram, describe how you would plot the magnetic field lines on the card .
(b) Sketch the magnetic field patterns around both the sections of the wire. Use your sketch to explain why the two sections repel each other.
(c) The repulsive force between the two sections is small. What changes could be made to increase it?
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.
- What is meant by electric current?
- Name and define its unit.
- Which instrument is used to measure the electric current? How should it be connected in a circuit?
Match the items in column-I to the items in column-II:
| Column - I | Column - II |
| (i) electric current | (a) volt |
| (ii) potential difference | (b) ohm meter |
| (iii) specific resistance | (c) watt |
| (iv) Electrical power | (d) joule |
| (v) electrical energy | (e) ampere |
