SAMPLE PAPER 01 UKSSSC JUNIOR ENGINEER (ELECTRICAL)
- Increasing the number of turns of wire on the secondary of a transformer will
- increase the primary current
- increase the secondary current
- decrease the secondary current
- have no effect on the secondary current
- The transformer turns ratio determines
- the ratio of primary and secondary voltages
- the ratio of primary and secondary currents
- the reflected impedance
- all of the above
- Mutual induction is dependent on
- winding ratios
- output polarities
- dc voltage levels
- current changes
- A special transformer used to convert unbalanced signals to balanced signals is the
- Balun
- Autotransformer
- center-tapped transformer
- step-across transformer
- A transformer has
- primary and secondary windings, both of which are considered inputs
- primary and secondary windings, both of which are considered outputs
- a primary winding used as an output and a secondary winding used as an input
- a primary winding used as an input and a secondary winding used as an output
- If the primary power of an ideal transformer having a 2:1 voltage ratio is 100 W, the secondary power is
- 100 W
- 50 W
- 75 W
- 200 W
- When transistors are used in digital circuits they usually operate in the:
- active region
- breakdown region
- saturation and cutoff regions
- linear region
- Three different Q points are shown on a dc load line. The upper Q point represents the:
- minimum current gain
- intermediate current gain
- maximum current gain
- cutoff point
- A transistor has a
of 250 and a base current, IB, of 20
A. The collector current, IC, equals:
- 500
A
- 5 mA
- 50 mA
- 5 A
- 500
- Junction Field Effect Transistors (JFET) contain how many diodes?
- 4
- 3
- 2
- 1
- D-MOSFETs are sometimes used in series to construct a cascode high-frequency amplifier to overcome the loss of:
- low output impedance
- capacitive reactance
- high input impedance
- inductive reactance
- A JFET
- is a current-controlled device
- has a low input resistance
- is a voltage-controlled device
- is always forward-biased
- In a class B push-pull amplifier, the transistors are biased slightly above cutoff to avoid
- crossover distortion
- unusually high efficiency
- negative feedback
- a low input impedance
- Which of the following conditions are needed to properly bias an npn transistor amplifier?
- Forward bias the base/emitter junction and reverse bias the base/collector junction.
- Forward bias the collector/base junction and reverse bias the emitter/base junction.
- Apply a positive voltage on the n-type material and a negative voltage on the p-type material.
- Apply a large voltage on the base
- The depletion-mode MOSFET
- can operate with only positive gate voltages
- can operate with only negative gate voltages
- cannot operate in the ohmic region
- can operate with positive as well as negative gate voltages
- In the constant-current region, how will the IDS change in an n-channel JFET?
- As VGS decreases ID decreases.
- As VGS increases ID increases.
- As VGS decreases ID remains constant.
- As VGS increases ID remains constant
- To operate properly, a transistor's base-emitter junction must be forward biased with reverse bias applied to which junction?
- collector-emitter
- base-collector
- base-emitter
- Collector-base
- With the E-MOSFET, when gate input voltage is zero, drain current is:
- at saturation
- zero
- IDSS
- widening the channel
- A very simple bias for a D-MOSFET is called:
- self biasing
- gate biasing
- zero biasing
- voltage-divider biasin
- When a silicon diode is forward biased, what is VBE for a C-E configuration?
- voltage-divider bias
- 0.4 V
- 0.7 V
- emitter voltage
- Which JFET configuration would connect a high-resistance signal source to a low-resistance load?
- source follower
- common-source
- common-drain
- common-gate
- The transconductance curve of a JFET is a graph of:
- IS versus VDS
- IC versus VCE
- ID versus VGS
- ID × RDs
- With a PNP circuit, the most positive voltage is probably:
- Ground
- VC
- VBE
- VCC
- Filters are used to convert
- Pulsating dc signal into a pure dc signal
- Pure dc signal into a pulsating dc signal
- Pulsating dc signal into a pure ac signal
- Pulsating ac signal into a pure dc signal
- The cut - in voltage for silicon and germanium are
- 0.3 V, 0.3 V
- 0.3 V, 0.7 V
- 0.7 V, 0.7 V
- 0.7 V, 0.3 V
- The P - type semiconductor impurities are also called as
- Acceptor impurities
- Donor impurities
- Either (a) or (b)
- None of these
- In N - type semiconductor, the impurities added to a semiconductor are
- Trivalent
- Pentavalent
- Monovalent
- Tetravalent
- Impurities are generally added in the pure semiconductor to
- increase the number of electrons
- increase the number of holes
- increase their conductivity
- all of these
- In DOL fuses are provided to protect against
- Short circuit protection
- Over voltage
- Over current
- Over load
- The overload release protects the motor against
- Over voltage
- Over current
- Over load
- All of these
- 3 - point starter is used to start the
- Series motor
- Shunt motor
- Compound motor
- Only (b) and (c)
- Lithium cells operates ranging from
- -25 ° C to 25 ° C
- -50 ° C to 25 ° C
- -50 ° C to 75 ° C
- -75 ° C to 75 ° C
- In leclanche cell, anode is packed in a porous pot containing
- manganese dioxide
- charcoal powder
- sulphur dioxide
- only (a) and (b)
- The handle of iron box is made up of
- Bakelite
- Ebonite
- Chromium
- Only (a) and (b)
- From full load to no load, the change of terminal voltage is more in case of
- Lagging power factor
- Leading power factor
- Unity power factor
- Both lagging and leading power factor compared to unity power factor
- Buzzer in principle is a bell
- with hammer
- with gong
- with both hammer and gong
- without hammer and gong
- The net power in a series R-C circuit is
- Zero
- Positive
- Negative
- None of these
- The synchronous generator is also called an
- AC generator
- Alternator
- DC generator
- Only (a) and (b)
- The forward voltage drop across a diode is about....
- 2.5V
- 3V
- 10V
- 0.7V
- A semiconductor diode is used as
- An amplifier
- A Rectifier
- An oscillator
- A voltage regulator
- A semiconductor diode has ....
- One PN junction
- Two PN junction
- Three PN junction
- Four PN junction
- If the arrow of diode symbol is positive with respect to bar, then the diode is ....biased
- Forward
- Reverse
- Either forward or reverse
- None of the above
- If the temperature of the diode increases, then leakage current....
- Remains same
- Decreases
- Increases
- Becomes zero
- The output of an AND gate is LOW ________.
- all the time
- when any input is LOW
- when any input is HIGH
- when all inputs are HIGH
- A full subtracter circuit requires ________.
- two inputs and two outputs
- two inputs and three outputs
- three inputs and one output
- three inputs and two outputs
- Give the decimal value of binary 10010.
- 610
- 910
- 1810
- 2010
- A flip-flop has ________.
- one stable state
- no stable states
- two stable states
- none of the above
- What is a shift register that will accept a parallel input, or a bidirectional serial load and internal shift features, called?
- tristate
- end around
- universal
- conversion
- The output of an AND gate with three inputs, A, B, and C, is HIGH when ________.
- A = 1, B = 1, C = 0
- A = 0, B = 0, C = 0
- A = 1, B = 1, C = 1
- A = 1, B = 0, C = 1
- The output of a NOR gate is HIGH if ________.
- all inputs are HIGH
- any input is HIGH
- any input is LOW
- all inputs are LOW
Answer’s are marked Bold
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