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प्रश्न
Define the unit of current.
Define the S.I. unit of electric current.
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उत्तर
The unit of electric current is ampere (A). When one coulomb charge flows through an electric circuit in one second, then the electric current flowing through the circuit is said to be an ampere.
संबंधित प्रश्न
Calculate the number of electrons constituting one coulomb of charge.
How many milliamperes as there in 1 ampere?
Which unit could be used to measure current?
(a) Watt
(b) Coulomb
(c) Volt
(d) Ampere
How many electrons are flowing per second past a point in a circuit in which there is a current of 5 amp?
A p.d. of 6 V is applied to two resistors of 3 Ω and 6 Ω connected in parallel. Calculate:
(a) the combined resistance
(b) the current flowing in the main circuit
(c) the current flowing in the 3 Ω resistor.
If the lamps are both the same in the figure given below and if A1 reads 0.50 A, what do A2, A3, A4 and A5 read?
A cell supplies a current of 1.2 A through two 2 Ω resistors connected in parallel. When the resistors are connected in series, it supplies a current of 0.4 A. Calculate:
(i) the internal resistance and (ii) e.m.f. of the cell.
State the relation between work, charge and potential difference for an electric circuit.
Match the pairs.
| ‘A’ Group | ‘B’ Group |
| 1. Free electrons | a. V/R |
| 2. Current | b. Increases the resistance in the circuit |
| 3. Resistivity | c. Weakly attached |
| 4. Resistances in series | d. VA/LI |
Tick(✓) the correct choice in the following:
When the length of a conductor is doubled the resistance of the conductor
will
In a house there are 6 bulbs of 100 W each used for 4 hours a day, 4 bulbs of 60 W each used for 8 hours a day, an immersion heater of 2.5 kW used for 1 hour per day, and an electric iron of 800 W used for 2 hours per day. Calculate the cost of monthly electric bill for the month of April at the rate of 80 p per unit.
Explain with the help of a diagram how does 'short circuiting' occur in an electric kettle.
A 3 pin mains plug is fitted to the lead for a 1 kW electric kettle to be used on a 250 V A.C. supply. Which of the following statements is NOT correct?
(a) A 13 A fuse is the most appropriate value to use.
(b) The brown wire should be connected to the live side of the mains.
Fig . shows the core of a transformer and i ts input and output connections
State the material used for the core and describe th e structure of the core.
(a) Use the values given in the diagram to calculate the turns ratio for the transformer and connections, labeling all parts of the diagram .
(b) If a current of 2 A is taken from th e output, calculate th e current in the input circuit (Assume the transformer to be ideal ).
State whether the current is a scalar or vector?
Define the term kilowatt - hour and state its value in S.I. unit.
Study the following circuit and find out:
(i) Current in 12 Ω resistor.
(ii) The difference in the readings of A1 and A2, if any.
State expression for Cells connected in series.
An electrical appliance is rated at 1000 KVA, 220V. If the appliance is operated for 2 hours, calculate the energy consumed by the appliance in: (i) kWh (ii) joule.
Which of the following represents voltage?
Problems for practice:
If 5A current flows through a circuit, then convert the current in terms of microampere?
An ammeter is always placed in parallel with the circuit.
Calculate the current in a wire if a charge of 1500 coulomb flows through it in 5 minutes.
