Advertisements
Advertisements
Question
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?
Advertisements
Solution
Because three times the original length of the wire 10 cm is stretched to 30 cm
∴ Resistance becomes 9 times its resistance, i.e. 3 × 9 = 27 Ω
`"R"_1 = ρ 30/(a/3)`
= `9 [ρ 10/a]` ...(i)
`"R"_2 = ρ 10/a` put in (i)
R1 = 9R
= 9 × 3
= 27 Ω
∴ R = 3 Ω
APPEARS IN
RELATED QUESTIONS
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.
The relationship between the potential difference and the current in a conductor is stated in the form of a law.
1) Name the law.
2) What does the slope of V-I graph for a conductor represent?
3) Name the material used for making the connecting wire.
Write the SI unit of resistivity
A metal sphere is kept on an insulting stands. A negatively charged rod is brought near it, then the sphere is earthed as shown. On removing the earthing, and taking the negatively charged rod away, what will be the nature of charge on the sphere? Give reason for your answer.
Tick(✓) the correct choice in the following:
Ohm's law is applicable to
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?
Consider a current carrying wire (current I) in the shape of a circle. Note that as the current progresses along the wire, the direction of j (current density) changes in an exact manner, while the current I remain unaffected. The agent that is essentially responsible for is ______.
How is electric current related to the potential difference across the terminals of a conductor?
Draw a labelled circuit diagram to verify this relationship.
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.
