Advertisements
Advertisements
प्रश्न
State microscopic form of Ohm’s law.
Advertisements
उत्तर
Current density J at a point in a conductor is the amount of current flowing per unit area of the conductor around that point provided the area is held in a direction normal to the current.
J = `I/"A"`
Drift velocity, `"V"_"d" = "eE"/"m" tau`
I = `"neAV"_"d" = "neA" ("eA"/"m") tau ...["J" = "I"/"A"; sigma = ("ne"^2 tau)/"m"]`
`"I"/"A" = (("ne"^2tau)/"m")`E
J = σE
APPEARS IN
संबंधित प्रश्न
When a 12 V battery is connected across an unknown resistor, there is a current of 2.5 mA in the circuit. Calculate the value of the resistance of the resistor.
Calculate the current flowing through a wire of resistance 5 Ω connected to a battery of potential difference 3 V.
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?
Answer the following question.
Distinguish between Ohmic and non-ohmic substances; explain with the help of example.
The temperature of a conductor is increased. The graph best showing the variation of its resistance is:
Ohm's law deals with the relationship between ______
Let the resistance of an electrical device remain constant, while the potential difference across its two ends decreases to one fourth of its initial value. What change will occur in the current through it? State the law which helps us in solving the above stated question.
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.
The voltage - current readings of a certain material are shown in the table given below:
| Voltage (V) | 10 V | 20 V | 30 V |
| Current (I) | 2 A | 3 A | 4 A |
Study the table.
- State whether the conductor used is ohmic or non-ohmic.
- Justify your answer.
- State Ohm's law.
