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
Why are coils of electric toasters and electric irons made of an alloy rather than a pure metal?
What is Resistivity?
The graph between V and I for a conductor is a straight line passing through the origin.
What should remain constant in a statement of this law?
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?
Two metallic spheres A and B kept on insulating stands are in contact with each other. A positively charged rod P is brought near the sphere A as shown in the figure. The two spheres are separated from each other, and the rod P is removed. What will be the nature of charges on spheres A and B?
Fig. represents the circuit used for the verification of Ohm's law. Label the parts from A to F. state the function of each.
State the relation correlating the electric current flowing in a conductor and the voltage applied across it. Also, draw a graph to show this relationship.
State the limitations of Ohm’s law.
Draw a neat diagram for the verification of Ohm’s law by voltmeter-ammeter method. By another diagram show the relation between p.d. and current.
Choose the correct alternative.
Which of the following is an ohmic conductor?
Explain the equivalent resistance of a series resistor network.
Which of the following I-V graph represents ohmic conductors?
The variable resistance is called ____________.
The temperature of a conductor is increased. The graph best showing the variation of its resistance is:
Assertion: The statement of Ohm’s law is K = IR.
Reason: V = IR is the equation which defines resistance.
Calculate the total resistance of the circuit and find the total current in the circuit.
A metal rod of length 10 cm and a rectangular cross-section of 1 cm × `1/2` cm is connected to a battery across opposite faces. The resistance will be ______.
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.
You are provided with a resistor, a key, an ammeter, a voltmeter, four cells of 1.5 V each and few connecting wires. Using circuit components, draw a labelled circuit diagram to show the setup to study Ohm's law.
State the relationship between potential difference (V) across the resistor and the current (I) flowing through it. Also draw V-I graph, taking V on the X-axis.
Why should an ammeter have low resistance?
