A direct current can be measured by a D.C. potentiometer in conjunction with a standard resistance.
When the firing angle a of a single-phase, fully controlled rectifier feeding constant direct current into a load is 30°, the displacement power factor of the rectifier is
When the firing angle a of a single-phase, fully controlled rectifier feeding constant direct current into a load is 30°, the displacement power factor of the rectifier is √3/2
Direct Current (DC) Next Topic : Alternating current (AC)
Direct Current (DC) is the unidirectional electric current. Uni meaning is one. And the flow of charge in same direction. We know that conventional current flow from positive terminal of battery to ... The magnitude of DC may constant or vary but direction do not change with respect to time.
Describe the difference between direct and alternating current.
Direct current is the flow of electricity or charge in one direction.. Alternative current is the flow of charge that doesn't flow in one direction.
In the case of direct current?
In the case of direct current magnitude and direction of current remains constant.
Inductance affects the direct current flow?
Inductance affects the direct current flow at the time of turning on and off.
The self inductance of a coil can be measured using (A) Wien’s Bridge (B) Schering Bridge (C) Anderson’s Bridge (D) Wheatstone Bridge
The self inductance of a coil can be measured using Anderson’s Bridge
Resistances can be measured with the help of ohmmeters and resistance bridges.
Iron loss of a transformer can be measured by low power factor wattmeter.
Dielectric loss in a capacitor is best measured by (A) Wien Bridge (B) Schering Bridge (C) Anderson Bridge (D) Heaviside-Campbell Equal Ratio Bridge
Dielectric loss in a capacitor is best measured by Schering Bridge
E.m.f. of a Weston cell is accurately measured by electrostatic voltmeter.
True value has been 50 whereas measured value is 40 then the percentage error in the reading will be ______. (A) 20% (B) 40% (C) 50% (D) 30%
True value has been 50 whereas measured value is 40 then the percentage error in the reading will be 20%.
Alternating current is measured by induction ammeter.
The power consumed by a balanced 3-ph load is measured by two-wattmeter method. The meter readings are 8 kW and 4 kW. The power factor of the load is (A) zero (B) 0.5 (C) between zero and 0.5 (D) between 0.5 and unity
The power consumed by a balanced 3-ph load is measured by two-wattmeter method. The meter readings are 8 kW and 4 kW. The power factor of the load is between 0.5 and unity
With neat diagram explain calibration of energy meter by direct loading method.
Calibration of Energy Meter by Direct Loading Method: There are three methods for testing/calibration: 1. Long period dial test 2. Using rotary sub- standard meter 3. Using precision grade instruments All ... of substandard meter in kWh Then % error = [(D - DS)/DS] x 100
The load of a consumer is generally measured in terms of : (A) Volts (B) Amperes (C) Ampere hour (D) kW
The load of a consumer is generally measured in terms of : kW
In a battery, the difference between the no-load voltage and the measured voltage output is called ________ A) Internal voltage B) Internal resistance C) External resistance D) All the above
In a battery, the difference between the no-load voltage and the measured voltage output is called Internal resistance
Liquid flow rate is measured using (A) a pirani gauge (B) a pyrometer (C) an orifice plate (D) a bourdon tube
Liquid flow rate is measured using an orifice plate
Identify direct addressing instructions from following instructions : (i) MOV RO, R5 (ii) MOV RO, 80 H (iii) MOV RO, #75H (iv) ADD A, 45 H
Instructions ii) and iv) are direct addressing as 80H and 45H are direct addresses
A direct online starter is used for starting motors up to 5 H.P.
Differentiate between direct and indirect extrusion. Discuss their relative merits and demerits.
Direct extrusion Indirect extrusion Simple, but the material must slide along the chamber wall. In this case, material does not move but die moves. High friction forces must ... be used for extruding long extrudes. Support of the ram becomes a problem as work length increases.
Direct Extrusion process
Direct Extrusion process Direct extrusion process is shown in fig. The raw material used is a billet. It consists of a press operated ram and a cylinder or container into which the heated ... for extruding long extrudes. 2) Support of the ram becomes a problem as work length increases.
advantages and disadvantages of direct coupled amplifier over RC coupled amplifier.
Advantages: Due to absence of coupling capacitors, the gain does not reduce on the lower frequency side. This amplifier can amplify dc signals. Reduced cost and complexity due to absence of ... The output waveform has a dc shift. Poor frequency response at a higher frequency.
Explain with schematic diagram direct distribution of solar energy.
Explain with schematic diagram direct distribution of solar energy: Solar energy reaching earth's surface consists of two components: i) Direct solar energy, ii) Diffused solar energy. Direct solar energy ... radiation. It is very intense radiation and it can produce sun burns and shadows.
State the need of cascade amplifier and draw circuit diagram of 2-stage direct coupled amplifier.
Need:- The voltage (or power) gain, obtained from a single stage small signal amplifier, is limited. Therefore, it is not sufficient for all practical applications. Therefore, in order to obtain greater voltage and power gain, cascade amplifiers are used.
Compare RC coupled, transformer coupled and direct coupled amplifier based on four points.
Parameter RC coupled Transformer coupled Direct coupled Coupling element Resistor and capacitor Transformer No element Impedance matching Poor Excellent good Frequency ... Low frequency amplifier,opamp Size and cost small Large and bulky least
By use of thermocouple.
Diversity factor has direct effect on the fixed cost of unit generated.
For the protection of power station buildings against direct strokes the requirements are interception, conduction and dissipation.
An induction meter can handle current up to 100 A.
Eddy current damping cannot be used for moving iron instrument because
Eddy current damping cannot be used for moving iron instrument because the presence of a permanent magnet required for such purpose would affect the deflection and hence the reading of the instrument
The disc of an instrument using eddy current damping should be of conducting and non-magnetic material.
How can a magnetic field be used to generate an electric current?
Magnetic field can be used to generate electric current on a condition that it is on a rate of changing magnetic flux. (Faraday's law)
Precise control of reactive current flow entering the transmission and distribution systems can be minimized by using (A) synchronous condenser (B) static VAR capacitor (C) capacitor bank (D) thyristor switched reactor in parallel with capacitor
How eddy current can be minimized?
In a single-phase transformer, the magnetizing current is (A) in phase with the no-load current (B) in quadrature with the no-load current (C) the product of no-load current and power factor (D) in phase with the flux in the core
In a single-phase transformer, the magnetizing current is in phase with the flux in the core
The gravity controlled instrument has crowded scale because current is proportional to sine of deflection angle.
For measuring current at high frequency we should use thermocouple instrument.
The chemical effect of current is used in D.C. ammeter hour meter.
What type of meter is used to measure current?
Ammeter
The power delivered to a 3-phase load can be measured by the use of two wattmeters only when the (a) load is unbalanced (b) load is balanced (c) three phase load is connected to the source through three wires (d) three phase load is connected to the source through four wires
The power delivered to a 3-phase load can be measured by the use of two wattmeters only when the three phase load is connected to the source through three wires
The induction of a high Q inductor can be measured by a Hay Bridge.
The power of a n-phase circuit can be measured by using a minimum of (n - 1) wattmeter elements
The dielectric loss of capacitance can be measured by Schering bridge.
The resistance can be measured most accurately by bridge method.
Weins bridge
A 1000Ohm, 1 Watt resistor can safely pass a current of
A 1000 Ohm, 1 Watt resistor can safely pass a current of 30 mA
Can you make alternating current through a battery?
Yes, we can make AC through a battery using an inverter.
Which of the following can reduce the Eddy current losses? A) By making the core of a stack of plates electrically insulated from each other B) By making the core of solid block C) By increasing the applied voltage D) None of these
How can we increase the induced current?
Induced current can be increased by reducing no of windings on the secondary part compared to primary.
If the base current of a BJT is 250 µA and emitter current is 15 mA, then the common base current gain will be A) 0.98 B) 0.41 C) 59 D) 55
If the base current of a BJT is 250 µA and emitter current is 15 mA, then the common base current gain will be 0.98