Questions
A PN junction diode is connected to a battery of emf 5.5 V and external resistance 5.1 kΩ. The barrier potential in the diode is 0.4 V. The current in the circuit is
- 0.07843 mA
- 1.07 mA
- 927.27 A
- 28050 A
- 12750 A
The storage battery of a car has an emf of 12 V. If the internal resistance of the battery is 0.4, what is the maximum current that can be drawn from the battery?
- 30 A
- 0.033 A
- 48 A
- 4.8 A
- 0.33 A
A 500 watt toaster is connected to a 120 V household outlet, then calculate the resistance of the toaster.
- 28.8 ohm
- 7200 k ohm
- 0.034 ohm
- 4.166 ohm
- 0.24 ohm
A battery of emf 10 V and internal resistance 3 is connected to a resistor. If the current in the circuit is 0.5 A, what is the resistance of the resistor?
- 5 ohm
- 2 ohm
- 17 ohm
- 0.05 ohm
- 20 ohm
A negligibly small current is passed through a wire of length 15 m and uniform cross-section 6.0 × 10−7 m2 and its resistance is measured to be 5.0 Ω. Then calculate the resistivity of the wire.
- 2 × 10−7 Ω.m
- 450 × 10−7 Ω.m
- 0.5 × 10−7 Ω.m
- 0.5 × 107 Ω.m
- 18 × 107 Ω.m
If the cell is replaced by another cell, the balance point shifts to 60 cm. What is the emf of the second cell, if a potentiometer arrangement a cell of emf 1.25 V gives a balance point at 35 cm length of the wire?
- 1680 V
- 2.14 V
- 2625 V
- 0.0006 V
- 0.729 V
Calculate the effective capacitance of the combination in series with data C1 = 10μF; C2 = 5μF.
- 0.3 micro F
- 3.33 micro F
- 15 micro F
- 0.3 mega F
- 0.02 mega F
Calculate how many joules of energy will a 20 W lamp dissipate in one minute.
- 1200 J
- 20 J
- 0.33 J
- 3 J
- 0.05 J
If a current of 10 mA passes through your cell phone battery charger wire for 10 minutes, what quantity of electric charge is transferred through the wire to the battery?
- 6 C
- 0.000016 C
- 60000 C
- 1000 C
- 0.001 C
What is a resistor whose value of resistance depends on its temperature known as?
- LDR
- Strain guage
- Thermistor
- Preset
- VDR
In which form does the capacitor store energy within a dielectric between the conducting plates?
- Magnetic field
- Electric field
- Electromagnetic field
- Positive voltage
- Negative voltage
Three 3 ohm resistors are connected to form a triangle. The resistance between any two corners is
- 0.5 ohm
- 0.055 ohm
- 0.11 ohm
- 18 ohm
- 9 ohm
Calculate the rate at which heat is developed in the heater, if it has resistance 8 ohm and 15 ampere current passes through it for 2 hours.
- 3600 J
- 900 J
- 0.0011 J
- 0.016 J
- 60 J
Calculate the current flowing through the wire of charge 20 C when the time is 40 seconds.
- 0.50 Ampere
- 2 Ampere
- 800 Ampere
- 4 m Ampere
- 1 m Ampere
An electric locomotive has a maximum mechanical output of 4.0 MW. Electrical power is delivered at 25 kV from overhead wires. The overall efficiency of the locomotive in converting electrical power to mechanical power is 80%. What is the current from overhead wires, when locomotive is operating at its maximum power?
- 200 A
- 5 mA
- 6.25 mA
- 160 A
- 0.16 A
A conductor has a constant current of 5 A. How many electrons pass through a cross-section of the conductor in 3 minutes?
- 9.375 × 1019
- 1440 × 10-19 electrons
- 5.625 × 1021
- 0.106 × 10-19 electrons
- 24 × 10-19 electrons