Advertisements
Advertisements
Question
You have three resistors of values 2 Ω, 3 Ω, and 5 Ω. How will you join them so that the total resistance is less than 1 Ω? Draw a diagram and find the total resistance.
Advertisements
Solution
It is necessary to connect the resistors in parallel because we desire an effective resistance that is lower than the minimum value of the individual resistors.
∴ `1/"R" = 1/"R"_1 + 1/"R"_2 + 1/"R"_3`
`1/"R" = 1/2 + 1/3 +1/5`
= `(15 + 10 + 6)/30`
= `31/30`
∴ R = `30/31 < 1Ω`
R = 0.97 Ω
APPEARS IN
RELATED QUESTIONS
Show how you would connect three resistors, each of resistance 6 Ω, so that the combination has a resistance of 9 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?
Which of the following arrangement, A or B, has the lower combined resistance?
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 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?
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.
State how are the two resistors joined with a battery when potential difference is same across each resistor.
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.
A given wire is stretched to double its length. How will its resistance change?
Assertion: When a battery is short circuited, the terminal voltage is zero.
Reason: In a short circuit, the current is zero.
