2 - DC circuits

d

According to Kirchhoff's voltage law, the algebraic sum of all IR drops and e.m.f. in any closed loop of a network is always a. negative b. positive c. determine by battery e.m.fs d. zero

a

All good conductors have high a. conductance b. resistance c. reliance d. thermal conductivity

d

Four wires of same, the same cross-sectional area and the same length when connected in parallel give a resistance of 0.25Ω. If the same four wires are connected in series, the effective resistance will be a. 1Ω b. 2Ω c. 3Ω d.4Ω

c

If a circuit does not contain any source of energy or e.m.f., it is known as a. unilateral circuit b. bilateral circuit c. passive network d. active network

d

The substance which have a large number of free electrons and offer a low resistance are called a. insulators b. inductors c. semi-conductors d. conductors

c

Three 6 ohm resistors are connected to form a triangle. What is the resistance between any two concerns? a. 3/2Ω b.6Ω c. 4Ω d. 8/3 Ω

a

When a voltage of one volts is applied, a circuit allows one microampere current to flow through it. The conductance of the circuit is a. 1µ- mho b. 10⁶ mho c. 1 milli-mho d. none of these

c

When one leg of leg of parallel circuit is opened out the total current will a. reduce b. increase c. decrease d. become zero

d

Which of the following can have negative temperature coefficient? a. compounds of silver b. liquid metals c. metallic alloys d. electrolytes

b

"Any number of current sources in parallel may be replaced by a single current source whose current is the algebraic sum of individual sources currents and sources resistance is the parallel combination of individual source resistance" the above statement is associated with a. Thevenin's theorem b. Millman's theorem c. Maximum power transfer theorem d. none of the above

c

"In any linear bilateral network, if a source of e.m.f. E in any branch produces a current I in any other branch, then same e.m.f. acting in the second branch would produce the same current I in the first branch" The above statement is associated with a. compensation theorem b. superposition theorem c. reciprocity theorem d. none of the above

b

"Maximum power output is obtained from a network when the load resistance is equal to the output resistance of the network as seen from the terminals of the load" The above statement is associated with a. Millman's theorem b. Thevenin's theorem c. Superposition theorem d. Maximum power transfer theorem

b

A 40 W bulb is connected in series with a room heater. If now 40 W bulb is replaced by 100 W bulb, the heater output will a. decrease b. increase c. remain same d. heater will burn out

a

A delta circuit has each element of value R/2. The equivalent elements of star circuit will be a. R/6 b. R/6 c. 2R d. 3R

b

A start circuit has element of resistance R/2. The equivalent delta elements will be a. R/6 b. 3/2 R c. 2R d. 3R

c

An ideal voltage source should have a. large value of e.m.f. b. small value of e.m.f. c. zero source resistance d. infinite source resistance

d

An instrument which detects electric is known as a. voltmeter b. rheostat c. wattmeter d. galvanometer

b

An open resistor, when checked with an ohm-meter reads a. zero b. infinite c. high but within tolerance d. low but not zero

d

Efficiency of power transfer when maximum transfer of power occurs is a. 100% b. 80% c. 75% d. 50%

a

For maximum transfer of power, internal resistance of the source should be a. equal to load resistance b. less than the load resistance c. greater than the load resistance d. none of the above

b

For which of the following 'ampere second' could be the unit? a. reluctance b. charge c. power d. energy

a

If a wire conductor of 02 ohm resistance is doubled in length its resistance becomes a. 0.4 ohm b. 0.6 ohm c. 0.8 ohm d. 1.0 ohm

d

In a delta network each elements has value R. The value of each element in equivalent star network will be a. R/6 b. R/4 c. R/2 d. R/3

a

Kirchhoff's current law is applicable to only a. junction in a network b. closed loops in a network c. electric circuits d. electronic circuits

a

Ohm's law is not applicable to a. vacuum tubes b. carbon resistors c. high voltage circuits d. circuits with low current densities

b

The circuit whose properties are same in either direction is known aas a. unilateral circuit b. bilateral circuit c. irreversible circuit d. reversible circuit

d

The concept on which Superposition theorem is based is a. reciprocity b. duality c. non- linearity d. linearity

c

The property of a conductor due to which it passes current is called a. resistance b. reluctance c. conductance d. inductance

d

The rating of a fuse wire is always expressed in a. ampere-hours b. ampere-volts c. kWh d. amperes

a

The resistance of a few meters of wire conductor in closed electrical circuit is a. practically zero b. low c. high d. very high

b

The resistance of a parallel circuit consisting of two branches is 12ohms. If the resistance of one branch is 18 ohms, what is the resistance of the other? a. 18Ω b. 36Ω c. 48Ω d. 64Ω

a

The resistance of two wires is 25Ω when connected in series and 6Ω when joined in parallel. The resistance of each wire is the resistance of the other? a. 10Ω,15Ω b. 20Ω,30Ω c.5Ω,10Ω d. 10Ω,20Ω

c

The superposition theorem requires as many circuits to be solved as there are a. sources, nodes and meshes b. sources and nodes c. sources d. nodes

b

Three identical resistors are first connected in parallel and then in series. The resultant resistance of the first combination to the second will be? a. 9 times b. 1/9 times c. 1/3 times d. 3 times

b

To determine the polarity of the voltage drop across a resistor, it is necessary to know a. value of current through the resistor b. direction of current through the resistor c. value of resistor d. e.m.f. in the circuit

d

Two copper conductors have equal length. The cross sectional area of one conductor is four times that of the copper. If the conductor having smaller cross-sectional area has a rsistance of 40 omhs the resistance of other conductor will be a. 160 ohms b. 80ohms c. 20 ohms d. 10 ohms

b

Which is the best conductor of electricity? a. iron b. silver. C. copper d. carbon

d

Which of the following is non-linear parameter? a. inductance b. condenser c. wire wound resistor d. transistor

a

Which of the following materials had a negative temperature co-efficient of resistance? a. copper b. aluminium c. carbon d. brass

d

Which of the following materials has the least resistivity? a. zinc b. lead c. mercury d. copper

d

Which of the following statement is true both for a series and a parallel D circuit? a. elements have individual currents b. current are additive c. voltages are additive d. power are additive

b

You have to replace 1500Ω resistor in radio. You have no 1500Ω but have several 1000Ω ones which you would connect. a. two parallel b. two in parallel and one in series c. three in parallel d. three in series

b

resistance of a conductor varies inversely as a. length b. area of cross-section c. temperature d. resistivity