Advertisements
Advertisements
Question
Answer the following question.
While studying the dependence of potential difference ( V) across a resistor on the current (I) passing through it, in order to determine the resistance of the resistor, a student took 5 readings for different values of current and plotted a graph between V and t. He got a straight line graph passing through the origin. What does the straight-line signify? Write the method of determining the resistance of the resister using this graph.
Advertisements
Solution
The straight-line graph between the potential difference ( V) and current(I) shows that resistor is a linear element and follows Ohm's Law.
Calculation of Resistance: At any point on the graph, resistance is given as,
`"R" = ("V"_° ("value of potential difference at that point"))/("I"_° ("value of current at that point"))`
In other words, the Slope of the graph at any point gives the value `1/"R"`
Hence,
slope `="I"_°/"V"_° = 1/"R"`
`⇒ "R" = 1/"slope" =( "V"_° ("Value of Potential difference at that point"))/("I"_° ("Value of current at that point"))`
APPEARS IN
RELATED QUESTIONS
Write any two characteristics of a series combination of resistors.
If the length of a wire is doubled by taking more of wire, what happens to its resistance?
Write down an expression for the resistance of a metallic wire in terms of the resistivity.
Calculate the combined resistance in the given case:
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
State the order of resistivity of (i) a metal, (ii) a semiconductor and (iii) an insulator.
Name a substance of which the resistance remains almost unchanged by the increase in temperature.
What potential difference is needed to drive a current o f 1 A through a 5 Ω resistor?
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 wires of the same length and area made of two materials of resistivity ρ1 and ρ2 are connected in series to a source of potential V. The equivalent resistivity for the same area is:
