Subjective Assignment
BOARD LEVEL QUESTIONS ON FACTORS AFFACTING RESISTANCE AND RESISTIVITY
Q.1
Plot a graph to show the relationship of the resistivity of copper with temperature.
Q.2
Alloys of metals usually have (greater/less) resistivity than those of their constituent met2ls.
Q.3
Alloys usually have much (lower/higher) temperature coefficients of resistance then pure metals.
Q.4
‘Doping’ a semi-conductor (with small traces of impurity atoms) (reduces/increases) its resistivity.
Q.5
Graphite and most non-metals (increase/decrease) their resistance with increase in temperature.
Q.6
The resistivity of a semiconductor (increases/decreases) rapidly with increasing temperature.
Q.7
The resistivity of the alloy manganin (is nearly independent of/increases rapidly) with increase of temperature.
Q.8
The resistivity of a typical insulator (ex. amber) is greater/ smaller than that of a metal ? Why?
Q.9
What is conductance? What are the various units for conductance?
Q.10
Define temperature coefficient of resistance a. What are its units?
Q.11
State whether a is positive or negative for:
(i) copper,
(ii) silicon,
(iii) silver,
(iv) germanium, and
(v) carbon.
Q.12
Why alloys usually have high resistivity and low temperature coefficient than their constituent elements ?
Q.13
A wire of resistance 1 Q is stretched to double its length. What is the new resistance?
Q.14
Why the conductivity of a metallic conductor is more than that of an electrolyte ?
Q.15
Define resistance and resistivity of a conductor and give their dimensional formula.
Q.16
Give various factors which affect the resistance and resistivity of a conductor.
Q.17
What is the effect of temperature on the resistance of
(a) metallic conductor
(b) electrolyte
(c)semiconductor.
Q.18
Define temperature coefficient . State whether it is positive or negative for
(a) copper
(b) silicon
(c) germanium
(d) carbon.
Q.19
If the length of a wire is stretched by 1% what is the change in the resistance of wire?
Q.20
The temperature coefficient of a wire is 0.00125 / oC.At 300 K the resistance of the wire is 1W.Then find the temperature at which the resistance becomes 2W.
Q.21
A heating filament when connected to a source draw a current of 4.8A initially which finally settle down to 4A. If the temperature coefficient of the element is 4×10-4/ oC and the initial temperature is 30oC find the final temperature of the element.
Q.22
A battery supplies a current of 0.9 A through a 2W resistor and a current of 0.3 A through a 7W resistor. What is the internal resistance of the battery?
Q.23
Can we draw a current of 4amp through a cell of emf 10volt and internal resistance 4W.
Q.24
How can we connect two resistance so as to get minimum net resistance ?
Q.25
Why a HT battery should have high internal resistance ?
Q.26
Define internal resistance of a cell and give the factors on which it depends.
Q.27
Why it is easier to start a car on a hot day then in winters
Q.28
Why the headlights of a car become dim when its starter is operated ?
Q.29
Why the bulbs and light of a house gets dim for a short time when a high power appliance is switched on ?
Q.30
Find the resistance of the following resistors.
