Advertisements
Advertisements
Question
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?
Advertisements
Solution
According to Ohm’s law
V = IR
⇒ I = `V/R` …(1)
Now Potential difference is decreased to half
∴ New potential difference `"Vʹ" = V/2`
Resistance remains constant
So the new current `"Iʹ" = "Vʹ"/"R"`
= `(V/2)/R`
= `(1/2) (V/R)`
= `(1/2) I`
= `I/2`
Therefore, the amount of current flowing through the electrical component is reduced by half.
APPEARS IN
RELATED QUESTIONS
What is Resistivity?
An electrical bulb is marked 200V, 100W. Calculate the electrical resistance of its filament. If five such
bulbs are connected in series to a 200V supply, how much current will flow through them?
Find the expression for the resistivity of a material and state the SI unit of resistivity.
The unit of electrical resistance is:
(a) ampere
(b) volt
(c) coulomb
(d) ohm
How should the two resistances of 2 ohms each be connected so as to produce an equivalent resistance of 1 ohm?
- Draw a V-I graph for a conductor obeying Ohm’s law.
- What does the slope of V–I graph for a conductor represent?
In a conductor 6.25 × `10^16` electrons flow from its end A to B in 2 s. Find the current flowing through the conductor (e = 1.6 × `10^-19` C)
Consider the sacle of voltmeter shown in the diagram and answer the following questions :
(a) What is the least count of the voltmeter?
(b) What is the reading shown by the voltmeter ?
(c) If the voltmeter is connected across a resistor of 20 `Omega` how much current is flowing through the resistor?
Define the following:
Coulomb
What is meant by the drift speed of free electrons?
What are non-ohmic conductors? Give one exmaple. Draw a current-voltage graph for a non-ohmic conductor.
Answer the following question.
Distinguish between Ohmic and non-ohmic substances; explain with the help of example.
What is ohmic device?
Write a short note on superconductors?
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.
Which of the following is correct for V-I graph of a good conductor?
A metal rod of length 10 cm and a rectangular cross-section of 1 cm × `1/2` cm is connected to a battery across opposite faces. The resistance will be ______.
The voltage - current readings of a certain material are shown in the table given below:
| Voltage (V) | 10 V | 20 V | 30 V |
| Current (I) | 2 A | 3 A | 4 A |
Study the table.
- State whether the conductor used is ohmic or non-ohmic.
- Justify your answer.
- State Ohm's law.
A current of 3.2 mA flows through a conductor. If charge on an electron is −1.6 × 10-19 coulomb, find the number of electrons that will pass each second through the cross section of that conductor.
