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
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
Find the current in each resistor in the circuit shown below:
In the diagram shown below, the cell and the ammeter both have negligible resistance. The resistor are identical.
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.
Two resistances when connected in parallel give resultant value of 2 ohm; when connected in series the value becomes 9 ohm. Calculate the value of each resistance.
You are given three resistances of 1, 2 and 3 ohms. Shows by diagrams, how with the help of these resistances you can get:
(i) 6 Ω
(ii) `6/1` Ω
(iii) 1.5 Ω
Two exactly similar electric lamps are arranged (i) in parallel, and (ii) in series. If the parallel and series combination of lamps are connected to 220 V supply line one by one, what will be the ratio of electric power consumed by them?
A given wire is stretched to double its length. How will its resistance change?
In the figure below, the ammeter A reads 0.3 A. Calculate:
(i) the total resistance of the circuit
(ii) the value of R
(iii) the current flowing through R.
