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WorksheetsCircuits II SA2
Total questions: 60
Worksheet time: 47mins
A band pass filter passes?
only high frequencies
only low frequencies
a narrow band around one frequency
everything except one frequency.
A band stop filter passes?
Only low frequencies
Only hi frequencies
a narrow band around one frequency
everything except a narrow band around one frequency
What is the filter pictured?
Hi pass
Low pass
Fish tank filter
mustang air filter
What is the picture filter type?
Hi pass
Low pass
40 yard slant route pass
make a pass at a pretty girl
What is a band pass filters q factor?
The relative quality or 'size' of the bandwidth
The relative quotient of frequency response over impedance
The relative quantity of eggs that break in a dozen when you drop the crate
If an AC voltage is applied to an LCR circuit, which of the following is true?
I and V are out of phase with each other in R.
I and V are in phase in L while in C, they are out of phase.
I and V are out of phase in both C and L.
I and V are out of phase in L and in phase in C.
Choose the correct statement.
In a dc circuit the inductor can conduct but not a capacitor.
In dc circuit both the inductor and capacitor cannot conduct.
The inductor has infinite resistance in a dc circuit.
In a dc circuit capacitor has zero resistance
The reactance of a capacitor C is Xc. If both the frequency and capacitance be doubled, then new reactance will be
Xc
2Xc
4Xc
4Xc
The phase relationship between current and voltage in a pure resistive circuit is best represented by
Which of the following graphs represents the correct variation of inductive reactance XL with frequency u?
An AC voltage source of variable angular frequency ω and fixed amplitude Vm is connected in series with a capacitance C and an electric bulb of resistance R (inductance zero). When ω is increased then,
The bulb glows dimmer
Total impedance of the circuit increases
No change
The bulb glows brighter
To reduce the resonant frequency in an LCR series circuit with a generator
dielectric in the capacitor should be removed.
the iron core of the inductor should be removed.
the generator frequency should be reduced.
another capacitor should be added in parallel to the first.
In an alternating current circuit consisting of elements in series, the current increases on increasing the frequency of supply. Which of the following elements are likely to constitute the circuit?
only resistor
resistor and an inductor
only inductor
resistor and a capacitor
The winding of wire around a core which is connected to a source of energy is called the ....... coil.
primary
secondary
tertiary
Calculate potential difference in the secondary coil based on the information given below.
Vp = 240 V
Np = 20
Ns = 125
Vs ?
1500
500
1000
2000
What is the material used for construction of transformer core?
Aluminium
Copper
Iron
Wood
This picture is an example of a ________________.
Motor
Generator
Step-up transformer
Step-down transformer
A transformer has 100 turns in the primary coil and 25 turns in the secondary coil. When a 120 V is applied to the primary coil, what is the voltage in the secondary coil?
480V
30V
20V
450V
Can you produce current in a wire with a magnet that is sitting still?
Yes; having a magnet near a wire is enough to excite the electrons
No; the magnetic field has to be changing to excite the electrons
No; magnets cannot create electricity
Can you produce current in a wire with a magnet that is sitting still?
Yes; having a magnet near a wire is enough to excite the electrons
No; the magnetic field has to be changing to excite the electrons
No; magnets cannot create electricity
A coil spins in a magnetic field. Of the following
which causes an increase in the induced EMF in
the coil?
Spinning the coil faster
Removing the coil from the magnetic field
Keeping the flux at a constant rate
Decreasing the number of turns of wire in
the coil
Magnetic flux is related to magnetic field strength by the formula
Φ=BA
Φ=BA2
Φ=B/A
Φ=B/A2
When a charged particle moving with velocity v enters a magnetic field at right angles it will be forced into a circular path with radius r given by
mv/Bq
Bq/mv
mv2/Bq
none of these
The size of the force exerted on a moving charge relative to an external magnetic field is given by
Bqv
Bqvcosθ
Bqvsinθ
none of these
A uniform magnetic field of strength 4 mT is used to deflect a beam of electrons into a circular path of diameter 65 mm. Calculate the speed of the electrons
2.3x107ms-1
4.6x107ms-1
3.0x107ms-1
2.0x107ms-1
What does the direction of the pointing fingers mean in this picture?
the direction of the voltage
the rotation of the wire
the direction of the magnetic field
the direction of the current
F = BIL If the current and magnetic field are doubled, the magnetic force on the wire
halves
remains the same
doubles
quadruples
F = qvB If the speed and charge double, what happens to the magnetic force?
halves
remains the same
doubles
quadruples
As the switch is closed, the lamp will
Glow instantly
Glow gradually
Glow then go dim
Never light up.
After the switch is has been closed for a very long time, it is opened, what will the lamp do?
It glows
It doesn't glow
gradually goes dim
Dims then gradually glows
Magnetic flux depends on
Magnetic Field
Area
Angle between Magnetic Field and Area Vector
All of the above
Mutual inductance between two magnetically coupled coils depends on
Permeability of the core material
Number of turns of the coils
Cross sectional area of their common core
All of the above
An ideal transformer is a fictional lossless transformer whose coupling coefficient is (a) .
In an ideal transformer is lossless, the winding resistances equal ______, and _____ of the power delivered to the primary is delivered to a load connected to the secondary
one; most
zero; all
one; all
zero; most
Time-varying magnetic fields in an iron-core transformer produce
(a) currents and attendant losses in the core material.
A real-life transformer does not pass DC. What can you say about this statement?
It is always true.
It is sometimes true.
It is always false.
Its truth cannot be determined.
The ideal transformer is a somewhat realistic model only for nearly linear (small-signal) operation of a very efficient (low-loss) (a) -core transformer.
An ideal transformer is a poor model for air-core transformers, whose coupling coefficients are _____________ unity.
smaller than
much smaller than
much greater than
greater than
equal to
(a) transformers are used to alter the apparent resistance presented to a source by a load, or the apparent output resistance of a source, in order to achieve maximum power transfer in cases where the source and load resistance are different and cannot be changed
Electric utilities use ______ transformers at the origins of long-distance transmission lines and _______ transformers at the destination.
impedance-matching; linear
step-down; step-up
step-up; step-down
linear; impedance-matching
The ground potential difference is effectively cut off from the rest of the circuit. A transformer used to achieve this is called a/n (a) transformer.
(a) transformers are used to attenuate electrical noise.
(a) are also used extensively in communications applications to either select a particular frequency of interest or to ignore (reject) frequencies that may be interfering with your equipment.
What are filters created by using resistors and capacitors or inductors and capacitors called
Active filter
Passive filter
Differential filter
All pass filter
Given the lower and higher cut-off frequency of a band-pass filter are 2.5kHz and 10kHz. Determine its bandwidth.
750 Hz
7500 Hz
75000 Hz
None of the mentioned
The critical frequency is defined as the point at which the response drops ________ from the passband. (Hint: db = 20 log X where X is the % of the maximum output voltage)
- 3 db
-20 db
-6 db
- 40 db
