Question:
A rod of a certain metal is $1.0\, m$ long and $0.6\, cm$ in diameter. Its resistance is $ 3.0 \times 10^3\, \Omega$
Another disc made of the same metal is $2.0\, cm$ in diameter and $1.0\, mm$ thick. What is the resistance between the round faces of the disc?
A rod of a certain metal is $1.0\, m$ long and $0.6\, cm$ in diameter. Its resistance is $ 3.0 \times 10^3\, \Omega$
Another disc made of the same metal is $2.0\, cm$ in diameter and $1.0\, mm$ thick. What is the resistance between the round faces of the disc?
Updated On: Dec 17, 2025
- $1.35 \times 10^{-8} \, \Omega $
- $2.70\times 10^{-7} \, \Omega $
- $4.05 \times 10^{-6} \, \Omega $
- $8.10 \times 10^{-5} \, \Omega $
Show Solution
Verified By Collegedunia
The Correct Option is B
Solution and Explanation
As, $R=\rho l / A=\rho l /\left(\pi d^{2} / 4\right)$
Resistance for a given material is directly proportional to the length and inversely proportional to the square of diameter of round faces.
So for the second rod, diameter is $2.0 / 0.6=10 / 3$ times diameter of the first one. and, length is $1.0 \,mm / 1 \,m =1 / 1000$ times the length of first one.
Thus resistance of the second rod is,
$\frac{1 / 1000}{(10 / 3)^{2}}=9 \times 10^{-5}$ times the resistance of the first one.
So resistance of the second rod is
$3 \times 10^{-3} \times 9 \times 10^{-5}=2.70 \times 10^{-7} \,\Omega$
Was this answer helpful?
0
0
Top BITSAT Physics Questions
- Two point charges $-q$ and $+ q$ are located at point's $(0, 0, - a)$ and, $(0, 0, a)$ respectively. The electric potential at a point $(0, 9, z)$, where $z > a$ is
- Which of the following must be known in order to determine the power output of an automobile?
- A large drop of oil (density $0.8 \,g / cm ^{3}$ and viscosity $\eta_{0}$ ) floats up through a column of another liquid (density $1.2\, g / cm ^{3}$ and viscosity $\eta_{L}$ ). Assuming that the two liquids do not mix, the velocity with which the oil drop rises will depend on :
- A body is projected vertically upwards at time $ t = 0$ and it is seen at a height $H$ at time $t_1$ and $t_2$ second during its flight. The maximum height attained is ($g$ is acceleration due to gravity)
- At what point of a projectile motion, acceleration and velocity are perpendicular to each other ?
View More Questions
Top BITSAT Questions
- Two point charges $-q$ and $+ q$ are located at point's $(0, 0, - a)$ and, $(0, 0, a)$ respectively. The electric potential at a point $(0, 9, z)$, where $z > a$ is
- Which of the following must be known in order to determine the power output of an automobile?
- A large drop of oil (density $0.8 \,g / cm ^{3}$ and viscosity $\eta_{0}$ ) floats up through a column of another liquid (density $1.2\, g / cm ^{3}$ and viscosity $\eta_{L}$ ). Assuming that the two liquids do not mix, the velocity with which the oil drop rises will depend on :
- A body is projected vertically upwards at time $ t = 0$ and it is seen at a height $H$ at time $t_1$ and $t_2$ second during its flight. The maximum height attained is ($g$ is acceleration due to gravity)
- At what point of a projectile motion, acceleration and velocity are perpendicular to each other ?
View More Questions
Concepts Used:
P-n Junction
A P-N junction is an interface or a boundary between two semiconductor material types, namely the p-type and the n-type, inside a semiconductor.
Biasing conditions for the p-n Junction Diode:
in p-n junction diode two operating regions are there:
- P-type
- N-type
There are three biasing conditions for p-n junction diode are as follows:
- Zero bias: When there is no external voltage applied to the p-n junction diode.
- Forward bias: P-type is connected to positive terminal of the voltage potential while n-type is connected to the negative terminal.
- Reverse bias: P-type is connected to negative terminal of the voltage potential while n-type is connected to the positive terminal.