Advertisements
Advertisements
प्रश्न
State the law of combination of resistances in parallel.
Advertisements
उत्तर
In a parallel combination, the voltage remains the same across each resistor but the current gets divided. Let I1, I2 and I3 be the current across resistors R1, R2 and R3, respectively.
`l=l_1+l_2+l_3`
`V=LR,V=L_1R_1,L_2R_2, V=L_3R_3`
`I=v/R,I_1 V/R_1, I_2=V/R_2,L_3 V/R_1`
Using thrsr value, We get:
`V/R=V/R_1+V/R_2+V/R^1`
`1/R=1/R_1+1/R_2+1/R_1`
So, the total resistance is the sum of the reciprocal of the individual resistances.
APPEARS IN
संबंधित प्रश्न
Differentiate between resistances in series and parallel.
How can three resistors of resistances 2 Ω, 3 Ω and 6 Ω be connected to give a total resistance of 4 Ω ?
Several electric bulbs designed to be used on a 220 V electric supply line are rated 10 W. How many lamps can be connected in parallel with each other across the two wires of 220 V line if the maximum allowable current is 5 A?
The equivalent resistance of the parallel combination of two resistors of 60Ω and 40Ω is _______.
A) 24Ω
(B) 100Ω
(C) 50 Ω
(D) 240Ω
A wire that has resistance R is cut into two equal pieces. The two parts are joined in parallel. What is the resistance of the combination?
An electric heater which is connected to a 220 V supply line has two resistance coils A and B of 24 Ω resistance each. These coils can be used separately (one at a time), in series or in parallel. Calculate the current drawn when:
(a) only one coil A is used.
(b) coils A and B are used in series.
(c) coils A and B are uses in parallel.
If current flows through two lamps arranged:
(a) in series,
(b) in parallel,
and the filament of one lamps breaks, what happens to the other lamp? Explain your answer.
Which of the following combinations have the same equivalent resistance between X and Y?
Calculate the equivalent resistance between the points A and B in Fig. if each resistance is 2·0 Ω.

A combination consists of three resistors in series. Four similar sets are connected in parallel. If the resistance of each resistor is 2 ohm, find the resistance of the combination.
A uniform wire with a resistance of 27 Ω is divided into three equal pieces and then they are joined in parallel. Find the equivalent resistance of the parallel combination.
A battery of e.m.f. 15 V and internal resistance 2 `Omega` is connected to tvvo resistors of 4 ohm and 6 ohm joined.
(i) In series,
(ii) In para 1 lel. Find in each case the electrica I energy spent per minute in 6 ohm resistor.
What are the advantages of a parallel connection?
Tick (✓) the correct choice among the following :
Consider two cases of two parallel current carrying conductors. Current in
th e same direction and currents in th e opposi te directions will produce
How does the resistance of a metallic wire depend on the length of wire?
What connection is used in domestic appliances and why?
A coil in the heater consumes power P on passing current. If it is cut into halves and joined in parallel, it will consume power:
Three resistors of 6Ω, 4Ω and 4Ω are connected together so that the total resistance is 8Ω. Draw a diagram to show this arrangement and give reason to justify your answer.
Two resistors having resistance 8 Ω and 12 Ω are connected in parallel. Find their equivalent resistance.
Four resistors each of resistance 5 Ω are connected in parallel. What is the effective resistance?
