Advertisements
Advertisements
Question
Two wires of same material and same lengths have radii in the ratio of 2 : 3, Compare their resistances.
Advertisements
Solution
Given: r1 : r2 = 2 : 3
Area of cross-section of wire = a = π r2
∴ a1 : a2 = `"r"_1^2 : "r"_2^2 = 4 : 9`
Resistance of wire R α `1/"a"`
∴ `"R"_1/"R"_2 = "a"_2/"a"_1 = 9/4`
RELATED QUESTIONS
An electrical appliance has a resistance of 25 Ω. When this electrical appliance is connected to a 230 V supply line, the current passing through it will be:
(a) 0.92 A
(b) 2.9 A
(c) 9.2 A
(d) 92 A
If five resistances, each of value 0.2 ohm, are connected in series, what will be the resultant resistance?
What possible values of resultant resistance one can get by combining two resistances, one of value 2 ohm and the other 6 ohm?
Calculate the combined resistance in the given case:
Two bulbs of 100 W and 40 W are connected in series. The current through the 100 W bulb is 1 A. The current through the 40 W bulb will be ______.
Why are thick copper wires used as connecting wires?
State expression for Resistance connected in parallel.
What is a resistance? Define it with respect to Ohm’s law,
Illustrate-combination of cells e.g., three cells, in parallel, explaining the combination briefly. Obtain an expression for current ‘i’ in the combination.
What should be the length of a nickel wire of area of cross-section 3 mm2 used for making a rheostat of 750 ohm? (ρ of nickle = 0.069 Ohm mm2/m)
