Advertisements
Advertisements
प्रश्न
Judge the equivalent resistance when the following are connected in parallel − (a) 1 Ω and 106Ω, (b) 1 Ω and 103Ω and 106Ω.
Advertisements
उत्तर
(a) When 1 Ω and 106 Ω are connected in parallel:
Let R be the equivalent resistance.
R2 = 106 Ω .....[given]
`1/"R" = 1/1 + 1/10^6`
`1/"R" = (10^6 + 1)/10^6`
R = `10^6/(1 + 10^6)` ≈ 1 Ω
R ≈ 1 Ω
Therefore, equivalent resistance ≈ 1 Ω
(b) When 1Ω, 103 Ω and 106 Ω are connected in parallel:
Let R be the equivalent resistance.
`1/"R" = 1/"R"_1 + 1/"R"_2 + 1/"R"_3`
R1 = 1 Ω .....[given]
R2 = 103 Ω
R3 = 106 Ω
`1/"R" = 1/1 + 1/10^3 + 1/10^6`
`1/"R" = (10^6 + 10^3 + 1)/10^6`
`1/"R" = 1001001/1000000`
R = `1000000/1001001` ≈ 0.999 Ω ≈ 1 Ω
R ≈ 1 Ω
APPEARS IN
संबंधित प्रश्न
Complete the following :-
(a)
Find the expression for resistors connected in series.
Find the equivalent resistance between A and B
An electrical appliance has a resistance of 25 Ω. When this electrical appliance is connected to a 230 V supply line, the current passing through it will be:
(a) 0.92 A
(b) 2.9 A
(c) 9.2 A
(d) 92 A
The substance having infinitely high electrical resistance is called:
(a) conductor
(b) resistor
(c) superconductor
(d) insulator
Name the material which is used for making the heating element of an electric iron.
How does the resistance of a wire change when:
its length is tripled?
Give the law of combination of resistances in series.
Draw a V-I graph for a conductor at two different temperatures. What conclusion do you draw from your graph for the variation of resistance of conductor with temperature?
State how are the two resistors joined with a battery when equivalent resistance is more than either of the two resistances.
State how are the two resistors joined with a battery when same current flows in each resistor.
Name the following substances:
(i) Showing low resistivity,
(ii) Showing very high resistivity,
(iii) Showing moderate resistivity.
You have three resistors of values 2 `Omega`, 3 `Omega`, and 5 `Omega`. How will you join them so that the total resistance is less than 2 `Omega`?
Two bulbs of 100 W and 40 W are connected in series. The current through the 100 W bulb is 1 A. The current through the 40 W bulb will be ______.
State a relation between electrical power, resistance and potential difference in an electrical circuit.
Six equal resistors of 1 ohm each are connected to form the sides of a hexagon ABCDEF. Calculate the resistance offered by the combination if the current enters at A and leaves it at D.
With the help of a circuit diagram derive the formula for the resultant resistance of three resistances connected:
- in series and
- in parallel
The resistance of the hot filament of the bulb is about 10 times the cold resistance. What will be the resistance of 100 W-220 V lamps, when not in use?
