Advertisements
Advertisements
Question
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.
Advertisements
Solution
(a) The resistors of 3 Ω and 6 Ω are connected in parallel. Therefore, their net resistance can be calculated as:
1/R = 1/R1 + 1/R2
Here, R1 = 3 Î
R2 = 6 Î
So:
1/R = (1/3) + (1/6)
1/R = (2 + 1)/6
1/R = 3/6
R = 2 Ω
(b) The current flowing through the main circuit,
I = V/R
I = 6/2 A
I = 3 A
(c) The current flowing in the 3 Ω resistor,
I = V/R
I = 6/3 = 2 A
APPEARS IN
RELATED QUESTIONS
Draw the electrical symbols of the following components and state its use:
Rheostat (variable resistance)
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?
Why should the resistance of:
a voltmeter be very large?
You can given one hundred 1 Ω resistors. What is the smallest and largest resistance you can make in a circuit using these?
What happens to the other bulbs in a series circuit if one bulb blows off?
Which is the better way to connect lights and other electrical appliances in domestic wiring: series circuits or parallel circuits? why?
Draw a circuit diagram showing two lamps, one cell and a switch connected in series.
How can you change the brightness of the lamp?
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.
Tell the odd one out. Give a proper explanation.
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.
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 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.
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.
What should I choose ___________________
b. for getting protection from electric current.
c. to measure the current in the circuit?
MCB is used to protect household electrical appliances.
One unit of electrical energy consumed is equal to 1000 kilowatt-hour.
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
