Test
Rectifiers. Determination of the parameters of low frequency alternating current pulses - Medical Physics -
Preguntas del test (16)
1Consider the alternating current (Fig. 3). What fraction of its period (T) does it take to reach from zero to half of its amplitude?(hint: sin300=1/2)
- A1/6 T
- B1/12 T
- C1/8 T
2What particles are the electric current carriers (charge carriers) in metals?
- AElectrons
- BIons
- CElectrons and holes
3For the photoelectric effect to take place, the wavelength (λ) of the incident light must satisfy the following inequality:
Where: ɸ is the minimum energy needed to remove an electron from metal (work function); h is Plank constant.- Aλ ≥ ɸ/h
- Bλ ≤ hc/ ɸ
- Cλ ≥ c/ɸ
4Electric current is measured in units of amps (A) which represent the following rate of change:
- ACharge per time, Q/t
- BEnergy per charge, E/Q
- CEnergy per distance, E/x
5Alternating current (AC):
- AChanges frequency with time
- BChanges power with time
- CChanges direction with time
6The Oscilloscope measures and displays the relationship between two variables, input (y-axis) andreference (x-axis). Choose the correct pair:
- ATime (input) vs Voltage (reference)
- BVoltage (input) vs Time (reference)
- CCurrent (input) vs Voltage (reference)
7The current carriers inside vacuum tubes are:
- AElectrons
- BIons
- CElectrons and holes
8The term ”charge carrier” refers to
- AStrictly to electrons and holes
- BStrictly to electrons and protons
- CAny particle that has an electric charge
9The term ”elementary charge“ refers to
- AThe charge of the electron
- BThe charge of any charge carrier
- CThe charge of any elementary particle
10If across 25Ohm resistor is applied 50V (DC) how many Amperes is the current that will flow:
- A20 mA
- B0.5 A
- C2 A
11What happens to the current (DC) in metallic conductor, if the voltage is doubled?
- AIt will be halved
- BIt will double
- CIt will stay the same
12Ohm’s Law states that the magnitude of the electric current is proportional to the applied voltage and inversely proportional to the resistance in the conducting material. Choose one:
- AI = V/R
- BI = R/V
- CI =V·R
13For Ohmic load in a DC circuit, what would be the change in power consumption if the voltage is halved?(hint: in Ohmic circuits the ratio V/I = constant, and power = V·I)
a. It will double- AIt will double
- BIt will be halved
- CIt will be quartered
14What is the resistance in a load if, when 120 V are applied, it draws a current of 20 Amps:
- A6 Ohms
- B60 Ohms
- C100 Ohms
15Metals are good conductors of electricity because:
- AThere are free electrons
- BThere are free electrons and protons
- CThere are electrons and positrons
16A 400 Ohm resistor draws 0.05 A direct current. What is the voltage across the resistor
- A2 V
- B20 V
- C200 V
Información
- Descripción
- Medical Physics Test sobre Rectifiers. Determination of the parameters of low frequency alternating current pulses - Medical Physics - , creado por Hussain Basheer el 23/11/2018.
- Autor
- Hussain Basheer
- Idioma
- English
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- 251
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