Advertisements
Advertisements
प्रश्न
A low voltage supply from which one needs high currents must have very low internal resistance. Why?
Answer the following giving reason:
A low voltage supply from which one needs high currents must have very low internal resistance. Why?
Advertisements
उत्तर
According to Ohm’s law, the relation for the potential is V = IR
Voltage (V) is directly proportional to the current (I).
R is the internal resistance of the source.
I = `V/R`
If V is low, then R must be very low, so that a high current can be drawn from the source.
संबंधित प्रश्न
The relationship between the potential difference and the current in a conductor is stated in the form of a law.
1) Name the law.
2) What does the slope of V-I graph for a conductor represent?
3) Name the material used for making the connecting wire.
Write the SI unit of resistivity
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?
- What should remain constant in a statement of this law?
The resistors R1, R2, R3 and R4 in the figure given below are all equal in value.
What would you expect the voltmeter A, B and C to read assuming that the connecting wires in the circuit have negligible resistance?
A resistance of 40 ohms and one of 60 ohms are arranged in series across 220 volt supply. Find the heat in joules produced by this combination of resistances in half a minute.
How would you connect two resistors in series? Draw a diagram. Calculate the total equivalent resistance.
Calculate the electric field in a copper wire of cross-sectional area 2.0 mm2 carrying a current of 1 A.
The resistivity of copper = 1.7 × 10–8 Ω m
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.
How does an increase in the temperature affect the specific resistance of a :
(i) Metal and
(ii) Semiconductor ?
Define the following:
Coulomb
The filament of a bulb takes a current 100 mA when potential difference across it is 0.2 V. When the potential difference across it becomes 1.0 V, the current becomes 400 mA. Calculate the resistance of filament in each case and account for the difference.
SI unit of resistance is:
State Ohm’s law.
Which of the following I-V graph represents ohmic conductors?
A student carries out an experiment and plots the V-I graph of three samples of nichrome wire with resistances R1, R2 and R3 respectively. Which of the following is hue?
The resistance of a resistor is reduced to half of its initial value. If other parameters of the electrical circuit remain unaltered, the amount of heat produced in the resistor will become ______.
Vinita and Ahmed demonstrated a circuit that operates the two headlights and the two sidelights of a car, in their school exhibition. Based on their demonstrated circuit, answer the following questions.
- State what happens when switch A is connected to:
a) Position 2
b) Position 3 - Find the potential difference across each lamp when lit.
- Calculate the current.
a) in each 12 Ω lamp when lit.
b) In each 4 Ω lamp when lit.
OR - Show, with calculations, which type of lamp, 4.0 Ω or 12 Ω, has the higher power.
