Advertisements
Advertisements
प्रश्न
How does the resistance of a wire change when:
its length is tripled?
Advertisements
उत्तर
Resistance,
`R=l/A`
where l = length of wire
A= area of cross-section of the wire
When the length is tripled, l' = 3l
New resistance,
`R'=l/A `
`R'=(rho(3l))/A=(3l)/A`
`R=3R`
`R=P/A`
Thus, the resistance will become three times the original resistance.
APPEARS IN
संबंधित प्रश्न
If the equivalent resistance is to be increased, then the number of resistances should be connected in
- Series
- Parallel
- Mixed arrangement
- None of the above
Find the equivalent resistance between A and B
Give one example to show how the resistance depends on the nature of material of the conductor.
V = IRTwo resistances X and Y are connected turn by turn : (i) in parallel, and (ii) series. In which case the resultant resistance will be less than either of the individual resistances?R = R1+ R2+ R3
A p.d. of 4 V is applied to two resistors of 6 Ω and 2 Ω connected in series. Calculate:
(a) the combined resistance
(b) the current flowing
(c) the p.d. across the 6 Ω resistor
You are supplied with a number of 100 Ω resistors. How could you combine some of these resistors to make a 250 Ω resistor?
Draw a V-I graph for a conductor at two different temperatures. What conclusion do you draw from your graph for the variation of resistance of conductor with temperature?
State the order of resistivity of (i) a metal, (ii) a semiconductor and (iii) an insulator.
State how are the two resistors joined with a battery when same current flows in each resistor.
What is the equivalent resistance between A and B in the given circuit (Fig?)
How will you oonnect five resistors, each of the value one ohm, to obtain an equivalent resistance of 0.2 `Omega`
Three resistors of 6.0 Ω, 2.0 Ω and 4.0 Ω are joined to an ammeter A and a cell of emf 6.0 V as shown in the following figure. Calculate :
- the effective resistance of the circuit.
- the reading of ammeter.
Name the material of wire used for making standard resistances. Give a reason.
Define the term resistivity and state its S.I. unit. Which will have higher resistivity a conductor or an insulator.
A metal wire of resistance 6 Ω is stretched so that its length is increased to twice its original length. Calculate its new resistance.
When a 4 Ω resistor is connected across the terminals of a 2 V battery, the number of coulombs passing through the resistor per second is:
Two electric bulbs have resistances in the ratio 1 : 2. If they are joined in series, the energy consumed in them is in the ratio:
