Advertisements
Advertisements
प्रश्न
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.
Advertisements
उत्तर
Let us first assume the equivalent internal resistance of the battery is Reff, the equivalent external resistance R and the equivalent voltage of the battery is Veff.
Now by applying Ohm's law,
Then current through R is given by `I = (V_"eff")/(R_"eff" + R)`
Now according to the question if all the resistances and the effective voltage are increased n-times, then we have
`V_("eff")^("new") = nV_("eff"), R_("eff")^("new") = nR_("eff")`
And Rnew = nR
Then, the new current is given by
`I^' = (nV_("eff"))/(nR_("eff") + nR) = (n(V_("eff")))/(n(R_("eff") + R)) = ((V_("eff")))/((R_("eff") + R)) = I`
The last result of two equations is same, so we can say that current remains the same.
APPEARS IN
संबंधित प्रश्न
What will be the change in the current if the potential difference is kept constant and the resistance of the circuit is made four times?
- It will remain unchanged.
- It will become four times.
- It will become one-fourth.
- It will become half.
Write the SI unit of resistivity
Name the physical quantity whose unit is "ohm".
The graph between V and I for a conductor is a straight line passing through the origin.
Which law is illustrated by such a graph?
How should the two resistances of 2 ohms each be connected so as to produce an equivalent resistance of 1 ohm?
How much energy is consumed when a current of 5 amperes flows through the filament (or element) of a heater having resistance of 100 ohms for two hours? Express it in joules.
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.
How would you connect two resistors in series? Draw a diagram. Calculate the total equivalent resistance.
A wire has a length of 2.0 m and a resistance of 5.0 Ω. Find the electric field existing inside the wire if it carries a current of 10 A.
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?
Rewrite the following statement by selecting the correct option.
The S.I. unit of resistance is __________.
What is ohmic device?
Define temperature coefficient of resistance.
Two cells each of 5V are connected in series across an 8Ω resistor and three parallel resistors of 4Ω, 6Ω, and 12Ω. Draw a circuit diagram for the above arrangement. Calculate
- the current drawn from the cell
- current through each resistor
The temperature of a conductor is increased. The graph best showing the variation of its resistance is:
State Ohm’s law? How can it be verified experimentally? Does it hold good under all conditions? Comment.
How is electric current related to the potential difference across the terminals of a conductor?
Draw a labelled circuit diagram to verify this relationship.
A current of 3.2 mA flows through a conductor. If charge on an electron is −1.6 × 10-19 coulomb, find the number of electrons that will pass each second through the cross section of that conductor.
