Advertisements
Advertisements
Question
Keeping the p.d. constant, the resistance of a circuit is halved. The current will become:
(a) one-fourth
(b) four time
(c) half
(d) double
Advertisements
Solution
d) double
As we know from Ohm’s law:
Voltage = Current x Resistance
V = IR
If the voltage is constant, the resistance of the circuit is halved. That is, it becomes R / 2.
Current, I = V/R
I = V/R
I = V/R/2 = 2 I
Thus by keeping the p.d. constant, the resistance of a circuit is halved and the current is doubled.
APPEARS IN
RELATED QUESTIONS
Graph showing the variation of current versus voltage for a material Ga As is shown in the figure. Identify the region of
(i) negative resistance
(ii) where Ohm's law is obeyed.
Let the resistance of an electrical component remains constant while the potential difference across the two ends of the component decreases to half of its former value. What change will occur in the current through it?
The relationship between the potential difference and the current in a conductor is stated in the form of a law.
- Name the law.
- What does the slope of V-I graph for a conductor represent?
- Name the material used for making the connecting wire.
What is Resistivity?
Write the formula of resistivity
How should the two resistances of 2 ohms each be connected so as to produce an equivalent resistance of 1 ohm?
Four resistances of 16 ohms each are connected in parallel. Four such combinations are connected in series. What is the total resistance?
What is the necessary condition for a conductor to obey Ohm’s law?
A wire of resistance 3 ohm and length 10 cm is stretched to length 30 cm. Assuming that it has a uniform cross section, what will be its new resistance?
What length of copper wire of resistivity 1.7 × 10-8 Ω m and radius 1 mm is required so that its resistance is 2Ω?
Show by a diagram how two resistors R1 and R2 are joined in parallel. Obtain an expression for the total resistance of the combination.
State the limitations of Ohm’s law.
An ammeter placed in series with an electric radiator reads 0.5 amps and a voltmeter placed across it reads 230 volts. What is the resistance of the radiator?
Define temperature coefficient of resistance.
The slope of voltage (V) versus current (I) is called:
A student carries out an experiment and plots the V-I graph of three samples of nichrome wire with resistances R1, R2 and R3 respectively. Which of the following is hue?
Assertion: The statement of Ohm’s law is K = IR.
Reason: V = IR is the equation which defines resistance.
Suppose there is a circuit consisting of only resistances and batteries and we have to double (or increase it to n-times) all voltages and all resistances. Show that currents are unaltered. Do this for circuit of Example 3.7 in the NCERT Text Book for Class XII.
State Ohm's Law. Represent it mathematically.
Resistance (R) in a conductor is best described as:
