Advertisements
Advertisements
प्रश्न
Two conductors are made of the same material and have the same length. Conductor A is a solid wire of diameter 1 mm. Conductor B is a hollow tube of outer diameter 2 mm and inner diameter 1 mm. Find the ratio of resistance RA to RB.
Advertisements
उत्तर
We know that the resistance of wire is `R = ρ l/A` where A is cross-sectional area of conductor and ρ is the specific resistance or resistivity and L is the length of conductor.
The resistance of first conductor
`R_A = (ρl)/(pi(10^-3 xx 0.5)^2`
The resistance of second conductor,
`R_B = (ρl)/(pi[(10^-3)^2 - (0.5 xx 10^-3)^2]`
Now, the ratio of two resistors is given by
`R_A/R_B = ((10^-3)^2 - (0.5 xx 10^-3)^2)/(0.5 xx 10^-3)^2` = 3:1
APPEARS IN
संबंधित प्रश्न
A low voltage supply from which one needs high currents must have very low internal resistance. Why?
What is Resistivity?
Write the formula of resistivity
Name the unit of electrical resistance and give its symbol.
Ohm's law gives a relationship between:
(a) current and resistance
(b) resistance and potential difference
(c) potential difference and electric charge
(d) current and potential difference
Four resistances of 16 ohms each are connected in parallel. Four such combinations are connected in series. What is the total resistance?
State Ohm’s law and draw a neat labelled circuit diagram containing a battery, a key, a voltmeter, an ammeter, a rheostat and an unknown resistance to verify it.
A car bulb connected to a 12 volt battery draws 2 A current when glowing. What is the resistance of the filament of the bulb? Will the resistance be more same or less when the bulb is not glowing?
How would you connect two resistors in series? Draw a diagram. Calculate the total equivalent resistance.
A metal sphere is kept on an insulting stands. A negatively charged rod is brought near it, then the sphere is earthed as shown. On removing the earthing, and taking the negatively charged rod away, what will be the nature of charge on the sphere? Give reason for your answer.
- Name and state the law which relates the potential difference and current in a conductor.
- What is the necessary condition for a conductor to obey the law named above in part (a) ?
Explain the equivalent resistance of a series resistor network.
The temperature of a conductor is increased. The graph best showing the variation of its resistance is:
Calculate the total resistance of the circuit and find the total current in the circuit.
A heater of 220 V heats a volume of water m 5 mint time. A heater of 110 V heat in ten second. The resistance of the conductor is
The heat produced by a 100 w heater in 2 minute is equal to
State Ohm's Law. Represent it mathematically.
