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

1 Answer

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 effect will not occur when the frequency of the incident light is less than the threshold frequency as the electrons are unable to gain sufficient energy to overcome the electrostatic barrier of the work function of the metal.

Related questions

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 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 : 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 : 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 : The magnitude of saturation photo electric current depends upon (a) Frequency (b) Intensity (c) Work function (d) Stopping potential

Last Answer : Ans:(b)

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.

Last Answer : Answer: C

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 : What is threshold frequency?

Last Answer : Ans –The minimum frequency required to eject out electron from an atom.

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 : When iron rusts, its weight - (1) decreases (2) increases (3) Constant (4) None

Last Answer : (2) increases Explanation: Iron rust when they come into contact with water and oxygen. They rust faster in salty water or acid rain.

Description : Describe the process of photo emission. State the application of photo emission in electronic components

Last Answer : Process of Photoemission:when light of appropriate frequency and intensity is incident upon a surface of certain materials,the energy of light is given to electrons to leave the surface of metal ... photo tubes are used in door openers,counters, position and temperature control and colour analysis 

Description : 25 A step up transformer increases A. voltage B. current C. power D. frequency

Last Answer : A. Voltage

Description : 16.step-up transformer increases A. voltage B. current C. power D. frequency

Last Answer : A. Voltage

Description : Decreasing the frequency in a capacitive circuit while maintaining a constant circuit voltage, will result in a/an _____________. A. increase in apparent power B. decrease in circuit current C. decrease in capacitive reactance D. decrease in total impedance

Last Answer : Answer: B

Description : Load regulation is a measure of a power supplies ability keep a constant output under conditions of changing A) Line voltage B) Current demand C) Temperature D) Oscillator frequency.

Last Answer : A) Line voltage

Description : In a load flow analysis of a power system, the load connected at a bus is represented as a) Constant current drawn from the bus b) Constant impedance connected at the bus c) Voltage and frequency dependent sources at the boss d) Constant real and reactive power drawn from the bus

Last Answer : d) Constant real and reactive power drawn from the bus

Description : In the ________ algorithm of TCP, the size of the congestion window increases exponentially until it reaches a threshold A. slow-start B. congestion avoidance C. congestion detection D. none of the above

Last Answer : A. slow-start

Description : The following is true about actions of ethylalcohol: A. It exerts anticonvulsant action followed by lowering of seizure threshold B. It lowers pain threshold C. It increases confidence and reduces number of errors D. It increases heat production and helps to keep warm in cold weather

Last Answer : A. It exerts anticonvulsant action followed by lowering of seizure threshold

Description : Decision to stop testing should be based upon A. Successful use of specific test case design methodologies B. A percentage of coverage for each coverage category C. Rate of error detection falls below a specified threshold D. All of the above

Last Answer : D. All of the above

Description : The threshold effect in demodulators is a) The rapid fall of output SNR when the input SNR falls below a particular value b) Exhibited by all the demodulators when the input SNR is low c) Exhibited by all AM suppressed carrier coherent demodulators d) Exhibited by correlation receivers

Last Answer : The threshold effect in demodulators is The rapid fall of output SNR when the input SNR falls below a particular value

Description : In human relations the irritation threshold is the A. action that causes an annoyance. B. frequency of the annoying behavior. C. point at which a person notices something and becomes annoyed. D. lengt?

Last Answer : Need answer

Description : Compared with myelinated nerve fibres, non-myelinated nerve fibres : a. have a higher threshold for stimulation b. have a longer refractory period c. transmit impulses at a lower frequency d. all above

Last Answer : all above

Description : Pick up the correct statement from the following: (A) The minimum frequency of light for which no electrons are emitted, is called threshold frequency (B) Polarising angle of glass is 57.5° (C) At the polarising angle, the reflected and refracted rays are orthogonal (D) All the above

Last Answer : Answer: Option D

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 : Define : (i)Threshold frequency (ii)Work function

Last Answer : Threshold frequency: The minimum frequency of incident radiation at which emission of photoelectrons starts is called Threshold frequency.  Work function: The amount of energy required to detach the electron from metal surface is called work function. 

Description : Define Threshold voltage in CMOS?

Last Answer : The Threshold voltage, VT for a MOS transistor can be defined as the voltage applied between the gate and the source of the MOS transistor below which the drain to source current, IDS effectively drops to zero.

Description : Assume that the n-channel MOSFET shown in figure is ideal and that its threshold voltage is +1 .0 V. The voltage Vab between nodes a and b is A)5V B)2V C)1V D)0V

Last Answer : Assume that the n-channel MOSFET shown in figure is ideal and that its threshold voltage is +1 .0 V. The voltage Vab between nodes a and b is 0V

Description : Threshold voltage for PMOS is generally (A) Negative (B) Positive (C) Zero (D) None of the above

Last Answer : Threshold voltage for PMOS is generally Negative 

Description : The threshold voltage of an n- channel enhancement mode MOSFET is 0.5V when the device is biased at a gate voltage of 3V. Pinch off would be occurs at a drain voltage of (A) 1.5V (B) 2.5V (C) 3.5V (D) 4.5V

Last Answer : The threshold voltage of an n- channel enhancement mode MOSFET is 0.5V when the device is biased at a gate voltage of 3V. Pinch off would be occurs at a drain voltage of 2.5V

Description : What is the threshold voltage?

Last Answer : 440

Description : Substrate concentration at which an enzyme attains half its maximum velocity is (A) Threshold value (B) Michaelis-Menton constant (C) Concentration level (D) None of these

Last Answer : Answer : B

Description : Diagonal tension in a beam (A) Is maximum at neutral axis (B) Decreases below the neutral axis and increases above the neutral axis (C) Increases below the neutral axis and decreases above the neutral axis (D) Remains same

Last Answer : Answer: Option C

Description : The rating of the Transformer __ when the supply frequency is increased: a) Remains unchanged b) Increases c) Decreases d) None of the above

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 : If the spring mass system with m and spring stiffness k is taken to very high altitude, the natural frequency of longitudinal vibrations * 1 point (A) increases (B) decreases (C) remain unchanged (D) may increase or decrease depending upon the value of the mass

Last Answer : (C) remain unchanged

Description : If the mass of body increases A Frequency increases 4 times B Frequency decreases 4 times C Frequency become half D Frequency become double

Last Answer : C Frequency become half

Description : If the mass of body increases 4 times A Frequency increases 4 times B Frequency decreases 4 times C Frequency become half D Frequency become double

Last Answer : C Frequency become half