Advertisements
Advertisements
प्रश्न
A given wire is stretched to double its length. How will its resistance change?
Advertisements
उत्तर
When a given wire is stretched to double its length, its area of cross-section will be halved, so the resistance of wire will become four times.
संबंधित प्रश्न
With a neat labelled diagram and derive the equation for three resistances connected in parallel.
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?
A hot plate of an electric oven connected to a 220 V line has two resistance coils A and B, each of 24 Ω resistances, which may be used separately, in series, or in parallel. What are the currents in the three cases?
State the law of combination of resistances in parallel.
Show how you would connect two 4 ohm resistors to produce a combined resistance of (a) 2 ohms (b) 8 ohms.
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.
How does the resistance of a metallic wire depend on the length of wire?
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.
The least resistance obtained by using 2 Ω, 4 Ω, 1 Ω and 100 Ω is:
Two resistors of resistances 2 Ω and 3 Ω are connected in parallel to a cell to draw current 0.5 A from the cell. Draw a labelled diagram of the arrangement
