Description : The threshold frequency is the frequency below which - (1) photo current is constant (2) photo current increases with voltage (3) photo current decreases with volt (4) photo electric emission is not possible
Last Answer : (4) photo electric emission is not possible
Description : The threshold frequency is the frequency below which – (1) photo current increases with voltage (2) photo current decreases with voltage (3) photo electric emission is not possible (4) photo current is constant
Last Answer : (3) photo electric emission is not possible Explanation: The photoelectric effect is the emission of electrons by substances, especially metals, when light falls on their surfaces. The photoelectric ... gain sufficient energy to overcome the electrostatic barrier of the work function of the metal.
Description : The threshold frequency is the frequency below which : (1) photo current increases with voltage (2) photo current decreases with voltage (3) photo electric emission is not possible (4) photo current is constant
Last Answer : photo electric emission is not possible
Description : The reaction rate almost gets doubled for 10°C rise in temperature. This is due to the fact that the (A) Increased temperature reduces the activation energy (B) Fraction of molecules having threshold energy increases (C) Collision frequency increases (D) Value of threshold energy decreases
Last Answer : (B) Fraction of molecules having threshold energy increases
Description : The minimum frequency required to eject electrons from a metallic surface is called a) Critical frequency b) Peak value of frequency c) Threshold frequency d)Photo frequency
Last Answer : c) Threshold frequency
Description : The minimum energy required to eject an electron from a metal surface is called a) Intensity b) Threshold frequency c) Work function d) Photo energy
Last Answer : c) Work function
Description : A sine wave voltage is applied across an inductor. When the frequency of the voltage is decreased, the current decreases.
Last Answer : The question seems to be wrong. Increase in frequency would actually decrease the current through the Inductor. This happens because inductive reactance Xl is directly proportional to frequency. And if frequency increases the value of Xl would ... vice versa. Xl= 2*pi*f*L I=E/Z Z=sqrt(R^2+Xl^2)
Description : When the voltage remains constant, and the resistance increases in a series circuit, current flow _____________. A. decreases B. remains the same C. increases D. increases by the square
Last Answer : Answer: A
Description : When the voltage remains constant and the resistance is increased in a series circuit, the flow of current _____________. A. increases by the square of the original value B. increases C. remains the same D. decreases
Last Answer : Answer: D
Description : The emission of number of photo electrons depends upon a) The colour of the body b) The frequency of incident light c) The intensity of light d) All of the above
Last Answer : c) The intensity of light
Description : Which of the following is not a source of ozone emission in the atmosphere? (A) Refrigerators (B) Xerox machines (C) Dermatological photo-therapy equipments (D) High voltage electrical equipments
Last Answer : (A) Refrigerators
Description : The process, whereby electrons gain sufficient energy to be released from the surface of a thin, heated metal plate, is known as _____________. A. photo electric emission B. secondary emission C. thermionic emission D. regressive emission
Last Answer : Answer: C
Description : By accelerating the magnet inside the coil, the current in it A. increases B. decreases C. remains constant D. reverses
Last Answer : increases
Description : By increasing the current, the drift velocity A. decreases B. increases C. remains constant D. becomes zero
Last Answer : remains constant
Description : An LED is operated on a 12 volt automobile circuit. The voltage drop across the LED is 2 volts and the current must be limited to 50 milliamps to prevent its overheating and destruction. What size resistor must be used? w) 60 ohms x) 100 ohms y) 120 ohms z) 200 ohms
Last Answer : ANSWER: Z -- 200 OHMS
Description : An electric clothes dryer is connected to a 100-volt source. How much current does it use if it requires 2,000 watts of electric power?
Last Answer : 20 Amphere
Description : Electric current may be expressed in which one of the following units? w) coulombs/volt x) joules/coulomb y) coulombs/second z) ohms/second
Last Answer : ANSWER: Y -- COULOMBS/SECOND
Description : The threshold frequency is the frequency below which–
Last Answer : Photoelectric emission is not possible
Description : With increase in temperature, the rate constant obeying Arrhenius equation (A) Increases (B) Decreases (C) Decreases exponentially (D) Can either increase or decrease; depends on the frequency factor
Last Answer : (C) Decreases exponentially
Description : When a certain beam of light falls upon a metal surface, it ejects photoelectrons from it. The number of photoelectrons ejected per second by the beam of light depends upon one of the following. Is it ... the work function of the metal y) the frequency of the beam z) the intensity of the beam
Last Answer : ANSWER: Z -- THE INTENSITY OF THE BEAM
Description : The magnitude of saturation photo electric current depends upon (a) Frequency (b) Intensity (c) Work function (d) Stopping potential
Last Answer : Ans:(b)
Description : When a person sitting on a swing stands up on the swing, the frequency of oscillation – (1) decreases (2) increases (3) becomes infinite (4) does not change
Last Answer : (2) increases Explanation: In Simple Harmonic Motion, the frequency of the oscillation (1) is the number of oscillations per second which is expressed as f = 1/T where T is the time period (the time for the oscillator to complete one cycle).
Description : When a person sitting on a swing stands up on the swing, the frequency of oscillation (1) decreases (2) increases (3) becomes infinite (4) does not change
Description : The width of depletion layer of a P-N junction – (1) decreases with light doping (2) increases with heavy doping (3) is independent of applied voltage (4) is increased under reverse bias
Last Answer : (4) is increased under reverse bias Explanation: The total width of the depletion region is a function of applied reverse-bias and impurity concentration. Forward bias decreases the depletion region width whilst reverse bias increases it.
Description : The width of depletion layer of a P-N junction (1) decreases with light doping (2) increases with heavy doping (3) is independent of applied voltage (4) is increased under reverse bias
Last Answer : is increased under reverse bias
Description : 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.
Description : At boiling point of liquids, its – (1) Temperature increases (2) Atmospheric pressure increases (3) Temperature remains constant (4) Vapour pressure decreases
Last Answer : (3) Temperature remains constant Explanation: An interesting property of matter is that its temperature remains constant during a phase change, assuming its surrounding pressure is constant. A liquid changes into gaseous state at a constant temperature called its boiling point.
Description : Water flows through a horizontal pipe at a constant volumetric rate. At a location where the cross sectional area decreases, the velocity of the fluid: (1) increases (2) decreases (3) stays the same (4) none of the above
Last Answer : (1) increases
Description : If the temperature of a piece increases suddenly, the relative humidity– (1) increases (2) decreases (3) remains constant (4) fluctuates
Last Answer : (2) decreases Explanation: Relative humidity is the ratio of the partial pressure of water vapour in a airwater mixture to the saturated vapour pressure of water at a specific temperature.
Description : If the temperature of a place increases suddenly, the relative humidity – (1) Increases (2) Decreases (3) Remains constant (4) Fluctuates
Last Answer : (2) Decreases Explanation: Relative humidity is the ratio of the partial pressure of water vapor in an airwater mixture to the saturated vapor pressure of water at a prescribed ... of the system decreases because the saturated vapor pressure of water increases with increasing temperature.
Description : 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.
Description : As depth increases, pressure in a fluid A. increases B. decreases C. remains constant D. varies
Description : As distance increases, value of gravitational field strength A. also increases B. decreases C. remains constant D. may increase or decrease
Last Answer : decreases
Description : As the ball falls towards the ground, its velocity A. increases B. decreases C. remains constant D. becomes zero
Description : Assuming all other parameters remain constant, what happens to the pressure of a gas when the volume of the gas is increased? w) increases x) decreases y) fluctuates sinusoidally z) remains the same
Last Answer : ANSWER: X -- DECREASES
Description : After a projectile is fired horizontally near the earth's surface, the horizontal component of its velocity, neglecting any air resistance: w) increases steadily x) decreases steadily y) first decreases, then increases z) remains constant
Last Answer : ANSWER: Z -- REMAINS CONSTANT
Description : At boiling point of liquids, its (1) Temperature increases (2) Atmospheric pressure increases (3) Temperature remains constant (4) Vapour pressure decreases
Last Answer : Temperature remains constant
Description : When water freezes its density (1) Decreases (2) Becomes Zero (3) Remains constant (4) Increases
Last Answer : Decreases
Description : When a detergent is added to pure water, its surface tension (1) increases (2) decreases (3) remains constant (4) becomes infinite
Description : If the temperature of a place increases suddenly, the relative humidity (1) Increases (2) Decreases (3) Remains constant (4) Fluctuates
Description : For V/F control, when frequency is increased in transformer a) Core loss component current increases, Magnetizing component current decreases b) Core loss component current increases, ... component current decreases d) Core loss component current decreases, Magnetizing component current increases
Last Answer : Ans: Core loss component current decreases, Magnetizing component current decreases
Description : Which of the following statements is true concerning a stepdown transformer in an operating AC power circuit? A. Voltage and current will both be increased. B. Voltage and current will both be decreased C. Voltage decreases as current increases. D. Voltage increases as current decreases.
Description : According to Ohm’s law, what happens to circuit current if the applied voltage (a) increases, (b) decreases?
Last Answer : (a) Current increases (b) Current decreases
Description : If there is a reduction in the normally supplied frequency to a 120/240 volt, threephase AC current motor from 60 hertz to 55 hertz, the motor would _____________. A. run at a slower speed B. operate at a lower current C. overheat D. trip off the line
Description : As the temperature of the air increases from 0 degrees C to 20 degrees C, the wavelength of a sound made by a tuning fork of fixed frequency does which of the following? Does the wavelength w) increase x) decrease y) remain the same z) increase up to a maximum, then remain constant
Last Answer : ANSWER: W -- INCREASE
Description : A common-emitter circuit has an input voltage of 0.1 volt, an output voltage of 2.0 volts, an input current of 0.5 milliamps, and an output current of 10 milliamps. What is the power gain? A. 20 B. 40 C. 400 D. 4000
Description : A battery is connected to a circuit containing three resistors in parallel. The values of the three resistors are 2 ohms, 3 ohms, and 6 ohms. What is the voltage of the battery if the total circuit current is 12 amps? A. 2 volts B. 6 volts C. 12 volts D. 24 volt
Description : A device which can be used to check the calibration of a circuit breaker is a _________________. A. 500 volt megohmmeter B. portable low voltage high current testing unit C. standard digital multimeter D. clamp-on voltmeter
Last Answer : Answer: B
Description : To properly use a hook-on-type volt/ammeter to check current flow, you must FIRST _____________. A. de-energize the circuit to allow connection of the instrument in series B. hook the jaws ... test leads to the appropriate terminals D. short the test leads and calibrate the instrument to zero