Consider a resistor of uniform cross sectional area connected to a bat...
As the length is doubled, the cross section are of the wire becomes half, thus the resistance of the wire
becomes four times the previous value. Hence after the wire is elongated the current becomes one fourth. Electric field is potential difference per unit length and hence becomes half the initial value. The power delivered to resistance is
and hence becomes one fourth.
The correct answers are: the electric field in the wire will become half., the thermal power produced by the resistor will become one fourth.
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Consider a resistor of uniform cross sectional area connected to a bat...
Explanation:
When the length of the resistor is doubled by stretching it, several changes occur in the circuit. Let's analyze each option individually:
a) Current will become four times:
This option is incorrect. The current flowing through a resistor is given by Ohm's law: I = V/R, where I is the current, V is the voltage, and R is the resistance. As the length of the resistor is doubled, the resistance also doubles. Therefore, the current will decrease by half, not increase.
b) The thermal power produced by the resistor will become one fourth:
This option is correct. The thermal power produced by a resistor is given by P = I^2 * R, where P is the power, I is the current, and R is the resistance. As mentioned before, when the length of the resistor is doubled, the resistance also doubles. Therefore, the power will decrease by a factor of 4, since both the current and the resistance decrease by half.
c) The electric field in the wire will become half:
This option is correct. The electric field in a wire is given by E = V/L, where E is the electric field, V is the voltage, and L is the length of the wire. As the length of the resistor is doubled, the electric field will decrease by half, assuming the voltage remains constant.
d) The product of the current density and conductance will become half:
This option is incorrect. The product of the current density (J) and conductance (G) is given by J * G = I, where J is the current density and G is the conductance. Since the current (I) decreases by half when the length of the resistor is doubled, the product J * G will also decrease by half.
In conclusion, options b) and c) are the correct answers. The thermal power produced by the resistor will become one fourth, and the electric field in the wire will become half when the length of the resistor is doubled.