Advertisements
Advertisements
प्रश्न
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
उत्तर
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
संबंधित प्रश्न
Name the law which is illustrated by the above V−I graph.
A resistance of 40 ohms and one of 60 ohms are arranged in series across 220 volt supply. Find the heat in joules produced by this combination of resistances in half a minute.
In the circuit shown below in Fig, calculate the value of x if the equivalent resistance between A and B is 4 Ω.
Calculate the effective resistance across AB?
What is ohmic device?
The unit of specific resistance is ____________.
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?
Two cells of same emf E but internal resistance r1 and r2 are connected in series to an external resistor R (Figure). What should be the value of R so that the potential difference across the terminals of the first cell becomes zero.
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.
A current of 0.8 A flows in a conductor of 40 Ω for 1 minute. The heat produced in the conductor will be ______.
