Advertisements
Advertisements
प्रश्न
What will be the change in the current if the potential difference is kept constant and the resistance of the circuit is made four times?
- It will remain unchanged.
- It will become four times.
- It will become one-fourth.
- It will become half.
उत्तर
(c) It will become one-fourth.
According to Ohm’s law, the product of current and resistance should remain constant if the potential applied is the same. Hence, if resistance is made four times, then current should be one-fourth.
APPEARS IN
संबंधित प्रश्न
If the potential difference across the ends of a conductor is 220 V and the resistance of the conductor is 44 Ω (ohm), then the current flowing through is _________.
- 0.2 A
- 0.5 A
- 2 A
- 5 A
Will current flow more easily through a thick wire or a thin wire of the same material, when connected to the same source? Why?
When a 12 V battery is connected across an unknown resistor, there is a current of 2.5 mA in the circuit. Find the value of the resistance of the resistor.
A low voltage supply from which one needs high currents must have very low internal resistance. Why?
What is Resistivity?
Name the unit of electrical resistance and give its symbol.
Ohm's law gives a relationship between:
(a) current and resistance
(b) resistance and potential difference
(c) potential difference and electric charge
(d) current and potential difference
The unit of electrical resistance is:
(a) ampere
(b) volt
(c) coulomb
(d) ohm
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
What is the necessary condition for a conductor to obey Ohm’s law?
In an experiment of verification of Ohm’s law following observations are obtained.
Potential difference V (in volt) |
0.5 | 1.0 | 1.5 | 2.0 | 2.5 |
current I (in ampere) | 0.2 | 0.4 | 0.6 | 0.8 | 1.0 |
Draw a V-I graph and use this graph to find:
- the potential difference V when the current I is 0.5 A,
- the current I when the potential difference V is 0.75 V,
- the resistance in a circuit.
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?
In the circuit shown in the figure, find the total resistance of the circuit and the current in the arm AD.
Calculate the effective resistance across AB?
Define the following:
(i) Coulomb
(ii) Ohm
Fig. represents the circuit used for the verification of Ohm's law. Label the parts from A to F. state the function of each.
What is non-ohmic resistor?
What are non-ohmic conductors? Give one exmaple. Draw a current-voltage graph for a non-ohmic conductor.
Draw a neat diagram for the verification of Ohm’s law by voltmeter-ammeter method. By another diagram show the relation between p.d. and current.
SI unit of resistance is:
State microscopic form of Ohm’s law.
Obtain the macroscopic form of Ohm’s law from its microscopic form and discuss its limitation.
Explain the equivalent resistance of a parallel resistor network.
The resistance of a nichrome wire at 0°C is 10Ω. If its temperature coefficient of resistivity of nichrome is 0.004/ °C, find its resistance of the wire at boiling point of water. Comment on the result.
Two cells each of 5V are connected in series across an 8Ω resistor and three parallel resistors of 4Ω, 6Ω, and 12Ω. Draw a circuit diagram for the above arrangement. Calculate
- the current drawn from the cell
- current through each resistor
The unit of specific resistance is ____________.
The temperature of a conductor is increased. The graph best showing the variation of its resistance is:
Assertion: The statement of Ohm’s law is K = IR.
Reason: V = IR is the equation which defines resistance.
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 true?
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.
Let the resistance of an electrical device remain constant, while the potential difference across its two ends decreases to one fourth of its initial value. What change will occur in the current through it? State the law which helps us in solving the above stated question.
What is meant by resistance of a conductor ? Define its SI unit.
Why should an ammeter have low resistance?
Vinita and Ahmed demonstrated a circuit that operates the two headlights and the two sidelights of a car, in their school exhibition. Based on their demonstrated circuit, answer the following questions.
- State what happens when switch A is connected to:
a) Position 2
b) Position 3 - Find the potential difference across each lamp when lit.
- Calculate the current.
a) in each 12 Ω lamp when lit.
b) In each 4 Ω lamp when lit.
OR - Show, with calculations, which type of lamp, 4.0 Ω or 12 Ω, has the higher power.