Define resistance of a conductor. State the factors on which resistance of a conductor depends. Name the device which is often used to change the resistance without changing the voltage source in an electric circuit.
Calculate the resistance of $50 \,m$ length of wire of cross $-$ sectional area $0.01$ square $m m$ and of resistivity $5 \times 10^{-8}\, \Omega m$
Define resistance of a conductor. State the factors on which resistance of a conductor depends. Name the device which is often used to change the resistance without changing the voltage source in an electric circuit.
Calculate the resistance of $50 \,m$ length of wire of cross $-$ sectional area $0.01$ square $m m$ and of resistivity $5 \times 10^{-8}\, \Omega m$
It is defined as the opposition offered to the flow of current by a conductor.
It depends upon
$(i)$ nature of the material of the conductor,
$(ii)$ length of the conductor, and
$(iii)$ area of cross-section of the conductor.
A rheostat $/$ variable resistor is used to change the resistance in a circuit.
Given. $\quad L=50 m , A =0.01 mm ^{2}$
$=0.01 \times 10^{-6} m ^{2}$
$\rho=5 \times 10^{-8} \Omega m$
Using the relation $R =\frac{\rho L }{ A },$ we have
$R =\frac{5 \times 10^{-8} \times 50}{0.01 \times 10^{-6}}=250 \Omega$
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$(a)$ Calculate the resistance of the wire using the graph.
$(b)$ How many $176 \,\Omega$ resistors in parallel are required to carry $5\, A$ on a $220\, V$ line ?
$(c)$ Define electric power. Derive relation between power, potential difference and resistance.
$(a)$ Calculate the resistance of the wire using the graph.
$(b)$ How many $176 \,\Omega$ resistors in parallel are required to carry $5\, A$ on a $220\, V$ line ?
$(c)$ Define electric power. Derive relation between power, potential difference and resistance.