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प्रश्न
How does the resistance of a metallic wire depend on the thickness of wire?
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उत्तर
The resistance of a wire decreases with increase in its thickness (R ∝ l/a where a = πr2, the area of cross-section of the wire).
संबंधित प्रश्न
A resistor has a resistance of 176 ohms. How many of these resistors should be connected in parallel so that their combination draws a current of 5 amperes from a 220 volt supply line?
You are given three resistances of 1, 2 and 3 ohms. Shows by diagrams, how with the help of these resistances you can get:
(i) 6 Ω
(ii) `6/1` Ω
(iii) 1.5 Ω
Four resistors each of resistance 2Ω are connected in parallel. What is the effective resistance?
Five resistors, each 3 Ω, are connected as shown in Fig. Calculate the resistance
- between the points P and Q.
- between the points X and Y.
The circuit diagram Fig shows three resistors 2 Ω, 4 Ω and R Ω connected to a battery of e.m.f. 2 V and internal resistance 3 Ω. If main current of 0.25 A flows through the circuit, find:
- the p.d. across the 4 Ω resistor,
- the p.d. across the internal resistance of the cell,
- the p.d. across the R Ω or 2 Ω resistors
- the value of R.
State the S.I. unit of electrical resistance and define it.
Calculate equivalent resistance in the following cases:
A piece of wire having a resistance R is cut into five equal parts.
- How will the resistance of each part of the wire change compared with the original resistance?
- If the five parts of the wire are placed in parallel, how will the resistance of the combination change?
- What will be ratio of the effective resistance in series connection to that of the parallel connection?
Two resistors having resistance 8 Ω and 12 Ω are connected in parallel. Find their equivalent resistance.
