Advertisements
Advertisements
प्रश्न
How many electrons are flowing per second past a point in a circuit in which there is a current of 5 amp?
Advertisements
उत्तर
Current, I = 5 A
Time, t = 1 s
Using the relation, I = Q / t:
Q = I x t
= 5 x 1 = 5 C
Now, if the charge is `1.6xx10^-19C` the number of electrons is one.
So, if the charge is 5C, the number of electrons is given by:
`1/(1.6xx10^-19)xx5=31.25xx10^18`
APPEARS IN
संबंधित प्रश्न
Write down the formula which relates electric charge, time and electric current
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.
For a heater rated at 4 kW and 220 V, calculate:
(a) the current,
(b) the resistance of the heater,
(c) the energy consumed in 2 hours, and
(d) the cost if 1 kWh is priced at Rs 4.60.
Name two devices which work on the heating effect of electric current.
Calculate the effective resistance between the points A and B in the network shown below in Figure 8.45
In the network shown in the following adjacent Figure, calculate the equivalent resistance between the points.
- A and B
- A and C
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.
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 |
What is the function of a step-up transformer?
Electrical power P is given by the expression P = (Q × V) ÷ time
(a) What do the symbols Q and V represent?
(b) Express the power P in terms of current and resistance explaining the meanings of symbols used there in.
An electric bulb is marked '100 W, 250 V'. What information does this convey?
A current of 0.2 A flows through a wire whose ends are at a potential difference of 15 V. Calculate:
(i) The resistance of the wire, and
(ii) The heat energy produced in 1 minute.
Study the following circuit and find out:
(i) Current in 12 Ω resistor.
(ii) The difference in the readings of A1 and A2, if any.
An electrical gadget can give an electric shock to its user under certain circumstances. Mention any two of these circumstances.
True or False – If False give the correct answer
The representation of the electric current is A
Define an electric current.
State whether true or false. If false, correct the statement.
Current can produce magnetic field.
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 |
Conventionally, the direction of the current is taken as:
Match the following:
| 1. | 1 mA | a. | series |
| 2. | 1 pA | b. | ohmmeter |
| 3. | Ammeter | c. | 10-6 ampere |
| 4. | Electrical resistivity | d. | 10-3 ampere |
