Advertisements
Advertisements
प्रश्न
Consider a current carrying wire (current I) in the shape of a circle. Note that as the current progresses along the wire, the direction of j (current density) changes in an exact manner, while the current I remain unaffected. The agent that is essentially responsible for is ______.
पर्याय
source of emf.
electric field produced by charges accumulated on the surface of wire.
the charges just behind a given segment of wire which push them just the right way by repulsion.
the charges ahead.
Advertisements
उत्तर
Consider a current carrying wire (current I) in the shape of a circle. Note that as the current progresses along the wire, the direction of j (current density) changes in an exact manner, while the current I remain unaffected. The agent that is essentially responsible for is electric field produced by charges accumulated on the surface of wire.
Explanation:
Current per unit area (taken normal to the current), I/A, is called current density and is denoted by `vecJ`.
The SI unit of the current density ate A/m2. The current density is also directed along E and which is also a vector quantity and the relationship is given by
`vecJ = σvecE = vecE/ρ`
Where σ = conductivity and ρ = resistivity or specific resistance of the substance.
The `vecJ` changes due to the electric field produced by changes accumulated on the surface of wire.
APPEARS IN
संबंधित प्रश्न
If the potential difference across the ends of a conductor is 220 V and the resistance of the conductor is 44 Ω (ohm), then the current flowing through is _________.
- 0.2 A
- 0.5 A
- 2 A
- 5 A
Will current flow more easily through a thick wire or a thin wire of the same material, when connected to the same source? Why?
When a 12 V battery is connected across an unknown resistor, there is a current of 2.5 mA in the circuit. Find the value of the resistance of the resistor.
Name the physical quantity whose unit is "ohm".
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?
Which of the following is an ohmic resistance?
What length of copper wire of resistivity 1.7 × 10-8 Ω m and radius 1 mm is required so that its resistance is 2Ω?
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:
Explain the equivalent resistance of a series resistor network.
The resistance of a nichrome wire at 0°C is 10Ω. If its temperature coefficient of resistivity of nichrome is 0.004/ °C, find its resistance of the wire at boiling point of water. Comment on the result.
An electronics hobbyist is building a radio which requires 150 Ω in her circuit, but she has only 220 Ω, 79 Ω, and 92 Ω resistors available. How can she connect the available resistors to get the desired value of resistance?
The temperature of a conductor is increased. The graph best showing the variation of its resistance is:
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?
Calculate the total resistance of the circuit and find the total current in the circuit.
What is meant by resistance of a conductor ? Define its SI unit.
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 circuit depicted in the figure is employed for studying Ohm’s Law. Instead of using a standard resistor, a student opts for a glass tube filled with mercury (tube 1), connected to the circuit through two electrodes, E1 and E2. He records the readings of the ammeter and voltmeter, thereby calculating the resistance. The student repeats the experiment by substituting tube 1 with tube 2, where the same amount of mercury fills tube 2.
Neglecting internal resistance of the cell use (> or < or =) to compare:
- the resistance in both the cases.
- the voltmeter readings in both the cases.
- the specific resistance in both the cases.
