Advertisements
Advertisements
Question
A 4 Ω coil and a 2 Ω coil are connected in parallel. What is their combined resistance? A total current of 3 A passes through the coils. What current passes through the 2 Ω coil?
Advertisements
Solution
The coils of the resistors of 4 Ω and 2 Ω are connected in parallel. Therefore:
`1/R=1/R_1+1/R_2`
`1/R=1/4+1/2`
`1/R=3/4`
`R=4/3`Ω
Combined resistance of the 4 Ω coil and the 2 Ω coil = 1.33 Ω
Total current = 3 A
The voltage across the whole cicuit,as in case of parallel circuit volatge is same scross all resistances.
V = IR.
V = 3 x 4/3 = 4 V
Therefore, the current through the 2 Ω coil,
I = V/R1.
I = 4/2 A
I = 2 A
APPEARS IN
RELATED QUESTIONS
Complete the following :-
(b)
With a neat labelled diagram and derive the equation for three resistances connected in parallel.
The equivalent resistance of the parallel combination of two resistors of 60Ω and 40Ω is _______.
A) 24Ω
(B) 100Ω
(C) 50 Ω
(D) 240Ω
State the law of combination of resistances in parallel.
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?
Find the current in each resistor in the circuit shown below:
Explain with diagram what is meant by the "series combination" and "parallel combination" of resistances. In which case the resultant resistance is : (i) less, and (ii) more, than either of the individual resistances?
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?
Show with the help of diagrams, how you would connect three resistors each of resistance 6 Ω, so that the combination has resistance of (i) 9 Ω (ii) 4 Ω.
How will you connect three resistors of 2 Ω, 3 Ω and 5 Ω respectively so as to obtain a resultant of 2.5 Ω? Draw the diagram to show the arrangement.
Calculate the equivalent resistance between the points A and B in Fig. if each resistance is 2·0 Ω.
In the following figure calculate:
- the total resistance of the circuit
- the value of R, and
- the current flowing in R.
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.
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:
- the p.d. across the 4 Ω resistor,
- the p.d. across the internal resistance of the cell,
- the p.d. across the R Ω or 2 Ω resistors
- the value of R.
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, in parallel.
An electrical appliance having a resistance of 200 Ω is operated at 200 V. Calculate the energy consumed by the appliance in 5 minutes in kWh.
Solve the following question:
In an electric circuit, two resistors of 12 0 each are joined in parallel to a 6 V battery. Find the current drawn from the battery.
A given wire is stretched to double its length. How will its resistance change?
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?
Two resistors having resistance 8 Ω and 12 Ω are connected in parallel. Find their equivalent resistance.
