मराठी

State the Law of Combination of Resistances in Parallel. - Science

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 R1R2 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.

shaalaa.com
  या प्रश्नात किंवा उत्तरात काही त्रुटी आहे का?
पाठ 1: Electricity - Exercise 5

APPEARS IN

व्हिडिओ ट्यूटोरियलVIEW ALL [1]

संबंधित प्रश्‍न

An electric lamp of 100 Ω, a toaster of resistance 50 Ω, and a water filter of resistance 500 Ω are connected in parallel to a 220 V source. What is the resistance of an electric iron connected to the same source that takes as much current as all three appliances, and what is the current through it?


What are the advantages of connecting electrical devices in parallel with the battery instead of connecting them in series?


How can three resistors of resistances 2 Ω, 3 Ω and 6 Ω be connected to give a total resistance of 4 Ω ?


A hot plate of an electric oven connected to a 220 V line has two resistance coils A and B, each of 24 Ω resistances, which may be used separately, in series, or in parallel. What are the currents in the three cases?


Which of the following arrangement, A or B, has the lower combined resistance? 


A resistor has a resistance of 176 ohms. How many of these resistors should be connected in parallel so that their combination draws a current of 5 amperes from a 220 volt supply line?


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 and B are used in series.
(c) coils and B are uses in parallel.


Are the lights in your house wired in series?


Five resistors, each 3 Ω, are connected as shown in Fig. Calculate the resistance

  1. between the points P and Q.
  2. between the points X and Y.  

 


A particular resistance wire has a resistance of 3 ohm per meter. Find the total resistance of three lengths of this wire each 1.5 m long, joined in parallel.


Show how would you connect three resistors, each of resistance 6 O so that
the combination has a resistance of(a) 9 Ω (b) 4 .Ω


What are the advantages of a parallel connection?


The circuit diagram Fig shows three resistors 2 Ω, 4 Ω and R Ω connected to a battery of e.m.f. 2 V and internal resistance 3 Ω. If main current of 0.25 A flows through the circuit, find:

  1. the p.d. across the 4 Ω resistor,
  2. the p.d. across the internal resistance of the cell,
  3. the p.d. across the R Ω or 2 Ω resistors
  4. the value of R.

Calculate equivalent resistance in the following cases:


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 V-I graphs A and B for series and parallel combinations of two resistors are as shown. Giving reason state which graph shows (a) series, (b) parallel combination of the resistors.


A piece of wire of resistance R is cut into three equal parts. These parts are then connected in parallel. If the equivalent resistance of this parallel combination is R1, what is the value of the ratio R1 : R?


Study the following circuit:

On the basis of this circuit, answer the following questions:

i. Find the value of total resistance between the points A and B.

ii. Find the resistance between the points B and C.

iii. Calculate the current drawn from the battery, when the key is closed

OR

iii. In the above circuit, the 16Ω resistor or the parallel combination of two resistors of 8 Ω, which one of the two will have more potential difference across its two ends? Justify your answer.


Four resistors each of resistance 5 Ω are connected in parallel. What is the effective resistance?


Share
Notifications

Englishहिंदीमराठी


      Forgot password?
Use app×