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प्रश्न
How does the presence of impurities in a metal affect its resistance?
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उत्तर
The presence of impurities in a metal increases its resistivity (also resistance) and it does not undergo oxidation easily even at a high temperature.
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संबंधित प्रश्न
Write any two characteristics of a series combination of resistors.
Two resistors of 4Ω and 6 Ω are connected in parallel to a cell to draw 0.5 A current from the cell.
(i) Draw a labelled circuit diagram showing the above arrangement.
(ii) Calculate the current in each resistor. What is an Ohmic resistor?
Write down an expression for the resistance of a metallic wire in terms of the resistivity.
Give one example to show how the resistance depends on the nature of material of the conductor.
How does the resistance of a wire change when:
its diameter is tripled?
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
If two resistors of 25 Ω and 15 Ω are joined together in series and then placed in parallel with a 40 Ω resistor, the effective resistance of the combination is :
(a) 0.1 Ω
(b) 10 Ω
(c) 20 Ω
(d)40 Ω
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 how are the two resistors joined with a battery when same current flows in each resistor.
In series combination of resistances ______.
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 ______.
Name the material of wire used for making standard resistances. Give a reason.
The voltage applied to a given rheostat is made four times its initial value. By what factor will be resistance of the rheostat change?
Calculate the equivalent resistance between the points A and B for the following combination of resistors:
Calculate the equivalent resistance between P and Q from the following diagram:
Illustrate-combination of cells e.g., three cells, in series, explaining the combination briefly. Obtain an expression for current ‘i’ in the combination.
Two resistors of 4Ω and 6Ω are connected in parallel to a cell to draw 0.5 A current from the cell.
Draw a labelled circuit diagram showing the above arrangement.
Two resistors of 4Ω and 6Ω are connected in parallel to a cell to draw 0.5 A current from the cell. Calculate the current in each resistor.
With the help of a circuit diagram derive the formula for the resultant resistance of three resistances connected:
- in series and
- in parallel
