Advertisements
Advertisements
प्रश्न
A particular resistance wire has a resistance of 3·0 ohm per metre. Find the resistance of 5 m length of a wire of the same material, but with twice the area of cross section.
Advertisements
उत्तर
R = `ρ l/a` ...(i)
∵ the wire's substance is the same, ρ will stay the same
l1 = 5l and l = 1m, a1 = 2a
∴ R1 = ρ `l_1/a_1`
or R1 = ρ `(5l)/(2a)` ...(ii)
(ii) ÷ (i)
`"R"_1/"R" = (ρ(5l)/(2a))/(ρ(l)/(a)`
= `5/2`
R1 = `5/2 "R"`
= `5/2 xx (3.0)`
= 7.5 Ω
APPEARS IN
संबंधित प्रश्न
Complete the following :-
(b)
Show how would you join three resistors, each of resistance 9 Ω so that the equivalent resistance of the combination is
1) 13.5
2) 6 Ω
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.
In the circuit given below:
(a) What is the combined resistance?
(b) What is the p.d. across the combined resistor?
(c) What is the p.d. across the 3 Ω resistor?
(d) What is the current in the 3 Ω resistor?
(e) What is the current in the 6 Ω resistor?
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?
Four resistors each of resistance 2Ω are connected in parallel. What is the effective resistance?
In the following figure calculate:
- the total resistance of the circuit
- the value of R, and
- the current flowing in R.
Two resistors of resistance 4 Ω and 6 Ω are connected in parallel to a cell to draw 0.5 A current from the cell.
Draw a labeled diagram of the arrangement
How does the resistance of a metallic wire depend on the thickness of wire?
Four resistors each of resistance 5 Ω are connected in parallel. What is the effective resistance?
