When a motor is just started, back emf is almost ______: a. Infinite b. zero c. minimum d. maximum Last Answer : d. maximum
In the plane of AC generator coil is parallel to the field, then emf induced in coil is: a. maximum b. minimum c. zero d. intermediate Last Answer : b. minimum
In the plane of the A.C generator coil is perpendicular to the field, then induced emf in the coil is: a. Maximum b. minimum c. zero d. intermediate value Last Answer : b. minimum
If velocity of a conductor moving through a magnetic field ‘B’ is made zero, then Motional emf will be: a. –VBL b. –V/BL c. – BL/V d. zero Last Answer : a. –VBL
In an oil-lubricated journal bearing, coefficient of friction between the journal and the bearing. [IES-1995] (a) Remains constant at all speeds. (b) is minimum at zero speed and increases ... speed. (d) becomes minimum at an optimum speed and then increases with further increase in speed. Last Answer : (d) becomes minimum at an optimum speed and then increases with further increase in speed.
A wire loop is moved parallel to a uniform magnetic field. The induced emf in the loop: a. depends on the shape b. depends on area c. depends on nature of loop d. zero Last Answer : d. zero
Terminal potential difference of a battery is greater than its emf when a. the internal resistance of battery is infinite b. the internal resistance of battery is zero c. the battery is charged d. the battery is discharged Last Answer : c. the battery is charged
The induced emf is produced in a circuit due to: a. Initial magnetic flux b. final magnetic flux c. Change of magnetic flux d. constant magnetic flux Last Answer : d. constant magnetic flux
When two gases are mixed, the entroру (a) Remains constant (b) Decreases (c) Increases (d) Becomes zero Last Answer : Ans:(c)
When water freezes its density – (1) Decreases (2) Becomes Zero (3) Remains constant (4) Increases Last Answer : (1) Decreases Explanation: Water at ordinary temperatures contracts and in-creases in density as it is cooled, like most substances. But at about 4°C it reaches a maximum density and then decreases in density as it approaches the freezing point. This is referred to as anomalous property of water.
By increasing the current, the drift velocity A. decreases B. increases C. remains constant D. becomes zero Last Answer : remains constant
As the ball falls towards the ground, its velocity A. increases B. decreases C. remains constant D. becomes zero Last Answer : increases
When water freezes its density (1) Decreases (2) Becomes Zero (3) Remains constant (4) Increases Last Answer : Decreases
A wire of uniform area of cross-section A length L and resistance R is cut into two parts. Resistivity of each part a. remains the same b. is doubled c. is halved d. becomes zero Last Answer : a. remains the same
With increase in temperature, the thermal conductivity of most liquids (A) Increases (B) Decreases (C) Remain same (D) First increases upto a certain temperature and then becomes constant Last Answer : (C) Remain same
On increasing the reverse bias to a large value in a p-n junction diode current (a) Increases slowly (b) Remains fixed (c) Suddenly increases (d) Decreases slowly Last Answer : (c) Suddenly increases
In forward bias, the width of potential barrier __________ (a) Increases (b) decreases (c) remains same (d) no effect Last Answer : (b) decreases
The direction of induced EMF can be found with the help of - Last Answer : Lenz’s Law
The induced emf in a coil depends upon: a. Strength of magnetic field b. Resistance of the coil c. area of the coil d. All of them Last Answer : d. All of them
Which of the following will produce an induced emf: a. Changing area of coil b. Changing magnetic flux c. changing orientation of coil d. all of them Last Answer : c. changing orientation of coil
The phenomena of induced emf was observed by Faraday and Henry in: a. 1931 b. 1831 c. 1535 d. 1940 Last Answer : a. 1931
The phenomenon of producing emf in the coil due to change of current in the coil itself is called: a. mutual induction b. self-induction c. self-inductance d. mutual inductance Last Answer : d. mutual inductance
The current flowing in a coil due to induced emf depends upon: a. shape of coil b. resistance of coil c. area of coil d. magnetic flux Last Answer : a. shape of coil
A neon flashlight cell with an emf of 1.5V gives a current of 15A when connected directly to an ammeter of resistance 0.04?. Internal resistance of the cell is a. 0.0004? b. 0.06? c. 0.10? d. 0.13? Last Answer : b. 0.06?
With the increase of pressure, the boiling point of any substance - (1) Increases (2) Decreases (3) Remains Same (4) Becomes zero Last Answer : (1) Increases Explanation: The temperature stays the same until all the liquid has vaporized. As the temperature of a liquid rises, the pressure of escaping vapor also rises, and at the boiling point ... vapor is equal to that exerted on the liquid by the surrounding air, causing bubbles to form.
With the increase of pressure, the boiling point of any substance – (1) Increases (2) Decreases (3) Remains Same (4) Becomes zero Last Answer : (1) Increases Explanation: The temperature stays the same until all the liquid has vaporized. As the temperature of a liquid rises, the pressure of escaping vapor also rises, and at the boiling point ... vapor is equal to that exerted on the liquid by the surrounding air, causing bubbles to form.
The surface tension of water on adding detergent to it – (1) increases (2) decreases (3) no change (4) becomes zero Last Answer : (2) decreases Explanation: In the solid and liquid phase, water molecules are bonded to each other by virtue of an interaction between hydrogen atoms on one molecule and the oxygen atom of another - the process ... to as "hydrogen bonding." The result is a kind of "skin" on liquid water's surface.
.If we narrow the distance between two slits in Young’s experiment the fringes width __________. A. Increases B. Decreases C. Remains same D. becomes zero Last Answer : B. Decreases
The surface tension of water on adding detergent to it (1) increases (2) decreases (3) no change (4) becomes zero Last Answer : decreases
Thevelocityfactor of a transmissionline a. depends on the dielectric constant of the material used b. increases the velocity along the transmission line c. is govern by the skin effect d. is higher for a solid dielectric than for air Last Answer : a. depends on the dielectric constant of the material used
If magnetic field is doubled then magnetic energy density becomes: a. Four times b. Two times c. Three times d. Six times Last Answer : c. Three times
A solenoid has n turns and length l. If length is reduced to l/2 and turns are doubled then magnetic field B produced by it becomes equal to a) 2B b) 4B c) 1/2 B d) None of these Last Answer : a) 2B
A proton moves in a uniform magnetic field in a circular path of radius R. If the energy of proton is doubled then the new radius becomes a) R √2 b) 2R c) R 2 d) √2 R Last Answer : d) √2 R
Two electron beams move parallel to each other. The nature of force between them is a) Attractive b) Repulsive c) Dependent on magnitude of velocity d) None Last Answer : b) Repulsive
When a detergent is added to pure water, its surface tension – (1) increases (2) decreases (3) remains constant (4) becomes infinite Last Answer : (2) decreases Explanation: When Soaps and detergents are added to water, they weaken the strength of the skin on the water's surface due to surface tension by interfering with hydrogen bonding ... of the soap or detergent is also attracted to the water, thereby decreasing the surface tension.
When a catalyst increases the rate of forward reaction, the value of rate constant (A) Increases (B) Decreases (C) Remain same (D) Becomes infinite Last Answer : (A) Increases
When a detergent is added to pure water, its surface tension (1) increases (2) decreases (3) remains constant (4) becomes infinite Last Answer : decreases
An ideal gas is compressed in a cylinder so well insulated that there is essentially no heat transfer. The temperature of gas a. Remains constant b. increases c. decreases d. is basically zero Last Answer : increases
The termcritical angle describes a. the point at which light is refracted b. the point at which light becomes invisible c. the point at which light has gone from the refractive mode to the reflective mode d. the point at which light has crossed the boundary layers from one index to another Last Answer : c. the point at which light has gone from the refractive mode to the reflective mode
If a material object moves with the speed of light ‘c’ its mass becomes a) equal to its rest mass b) Four times of its rest mass c) Double of its rest mass d) Infinite Last Answer : d) Infinite
When a uniform magnetic field B is applied to a current carrying coil, the coil will rotate in such a manner that its plane a) becomes parallel to B b) becomes anti-parallel to B c) makes an angle of 600 with B d) becomes perpendicular to B Last Answer : d) becomes perpendicular to B
If the distance between the two charge bodies is halved, the force between them becomes: (a) Half (b) Four time (c) One fourth (d) Doubled Last Answer : (c) One fourth
Pick out the wrong statement. (A) When the concentration difference for the mass transfer becomes zero at the bottom of the gas absorption tower, then the upper end of the operating line touches the ... fixed gas flow rate, the slope of the operating line decreases, in case of gas absorption process Last Answer : (C) The operating line lies above the equilibrium curve in case of a gas desorber
With increase in the shear rate, the apparent viscosity of pseudo-plastic fluids (A) Increases (B) Decreases (C) Remain same (D) May increase or decrease; depends on the magnitude of shear rate Last Answer : (B) Decreases
The counter EMF produced in the windings of a DC motor is 'zero' when the ____________. A. armature has just begun to turn B. armature is not turning C. motor is almost up to rated speed D. motor is at rated speed Last Answer : Answer: B
How the magnitude of rotor emf is related to the slip in an I M? Last Answer : Rotor circuit emf per phase E2’=SE2
What is the effect on the magnitude of emf generated in an AC generator if the speed of rotation is increased? Last Answer : The magnitude of emf generated increases.
6 In a two winding transformer, the primary and secondary induced emf E1 & E2 are always A. equal in magnitude B. anti phase with each other C. in phase with each other D. determined by load on transformer secondary Last Answer : C. In phase with each other
The resistivity of ..... decreases with the increase in temp. a. gold b. silver c. copper d. silicon Last Answer : d. silicon
Which of the listed procedures is the best way to tell if a motor has become overloaded? A. Measure the current flow and compare it with the motor full load current flow as shown on the nameplate. ... Watch for telltale signs of smoke coming from the motor. D. Periodic opening of the O/L relay coil Last Answer : Answer: A