Lab 4 Flashcards by Michelle Melton

The ratio of the voltage to the current in an electrical circuit is called _____.

charge
resistance
electric potential difference
potential gradient 
power

resistance

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Across a given resistance the voltage decreases if the current (__).

increases
decreases
remains the same
is reversed 
equals the resistance

decreases

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Given I = electric current, R = resistance, V = electric potential, W = work, P = power, t = time, Q = electric charge and x^2 means X squared. Voltage is defined as

R/I
the difference in electric potential between two equipotential surfaces
W/Q^2
I^2 times R
V^2/R

the difference in electric potential between two equipotential surfaces

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Given I = electric current, R = resistance, V = electric potential, W = work, P = power, t = time, Q = electric charge and X^2 means X squared. Which of the following is an expression for electric power?

P = I^2 times R
P = W/Q
P = v^2 times R
P = I^2/R
P = W times Q

P = I^2 times R

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W = Q * I * t
W = V^2 * R * t
W = V^2 * I * t
W = I^2 * R * t
W = I^2 * Q * t

W = I^2 * R * t

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Voltmeters measure __ _____ while ammeters measure ______.

power…electric current
difference in electric potential…electric charge
voltage…resistance
difference in electric potential…electric current
power…voltage

difference in electric potential…electric current

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The time rate of flow of electric charge is called

voltage
current
resistance
Ohm's Law
Watt's Law

current

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The standard unit of electric current is called an ampere and it equals…

Volt 
Ohm 
joule
coulomb/second
Farad

coulomb/second

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An electric current is measured in standard units called

Coulombs
Volts
Amperes
Watts
Farads

Amperes

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The difference in electric potential energy per unit of charge is called

Current
Voltage
Resistance
Capacitance
Wattage

Voltage

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Across a given resistance the voltage increases if the current

increases
decreases
remains the same
is reversed 
equals the resistance

increases

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The voltage across the terminals of a fuse

equals the supply voltage
is zero
is one-half the supply voltage 
is not determined 
equals 120 volts

is zero

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Ohm’s law is not applicable to

DC circuits
High currents
Small resistors
Semiconductors

Semiconductors

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Ohm’s law is not applicable to

High currents
Small resistors
Light bulbs
Diodes 
Both c and d

Both c and d

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When resistors are combined in series, the total resistance

equals the sum of the individual resistance
is smaller than the smallest resistance
is zero
is not determined
equals120 ohms

equals the sum of the individual resistance

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An arithmetic rule to apply to any number of resistance connected in parallel with one another is that the equivalent sum of resistances

is larger than the largest resistance
equals the algebraic sum of resistances
equals the sum of reciprocals of individual resistances
is always less than the least of the resistances
equals the reciprocal of the sum of the resistances added in series

is always less than the least of the resistances

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Which statement is correct?

Voltage flows through a closed circuit
charge flows in a closed circuit
Resistance flows through an open circuit
current is the primary source of voltage

charge flows in a closed circuit

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When two lamps are connected in parallel to a battery, the total resistance that the battery senses is

More than the resistance of either lamp
Less than the resistance of either lamp
The average of the resistance of the two lamps
The sum of the resistance of the two lamps

Less than the resistance of either lamp

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When connected to the same voltage source a 100 Watt light bulb glows brighter than a 20 Watt light bulb. The resistance of the 100 Watt light bulb must be

the same
Less
greater
none of the above

Less

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As more light bulbs are put into a series circuit, the overall current from the power source

Stays the same
Increases
Decreases

Decreases

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As more light bulbs are put into a parallel circuit, the overall current from the power source

Stays the same
Increases
Decreases

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Increases

Instead of saying a light bulb uses up electricity, it would be better to say

Electric energy is transferred into another form
Current disappears into the light bulb
Electrons are taken out of the circuit and put somewhere else
The main power supply voltage is lowered by the light bulb

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Electric energy is transferred into another form

Light bulb A is rated at 60 W and light bulb B is rated at 100 W. Both are designated to operate at 110 V. Which statement is correct?

A) The 60 W bulb has a greater resistance and greater current than the 100 W bulb
B) The 60 W bulb has a greater resistance and smaller current than the 100 W bulb
C) The 60 W bulb has a smaller resistance and greater current than the 100 W bulb
D) The 60 W bulb has a smaller resistance and smaller current than the 100 W bulb
E) We need to know the resistivity of the filaments to answer this question

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B) The 60 W bulb has a greater resistance and smaller current than the 100 W bulb

Three resistors R1, R2 and R3 are connected in series. Their equivalent resistance is given by

(R1+R2+R3)/3
R1+R2+R3
(1/R1)+(1/R2)+(1/R3)
R1R2R3/(R1+R2+R3)

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R1+R2+R3

Three resistors R1, R2, and R3 are connected in parallel. Their equivalent resistance is given by (R1+R2+R3)/3 R1+R2+R3 (1/R1)+(1/R2)+(1/R3) R1R2R3/(R1R2+R2R3+R3R1)

R1R2R3/(R1R2+R2R3+R3R1)

Voltmeters measure __ while ammeters measure ___. power...electric current difference in electric potential...electric charge voltage...resistance difference in electric potential...electric current power...voltage

Difference in electric potential...electric current

Voltmeters must be connected ___ while ammeters must be connected ___ with the resistance of interest. ``` in parallel...in series in series...in parallel in series...in series in parallel...in parallel with the ammeter...in series ```

in parallel...in series

For resistors in parallel, the total resistance is _____ than the _____ resistor. greater. ........largest greater. ........smallest lower. ........smallest lower. ........oldest greater. ........shortest

lower.........smallest

In your lab experiment the voltmeter used to measure the voltage is ________ connected in parallel with the element of interest in the electrical circuit connected in series with the power supply connected in series with the another voltmeter connected in series with the ammeter connected in series with the resistance through which voltage was measured

connected in parallel with the element of interest in the electrical circuit

In your lab experiment, the ammeter used to measure the current is ____ connected across the power supply connected in parallel with the series combination of resistance connected across the resistance through which current was measured connected in series with the voltmeter connected in series with the resistance through which current was measured

connected in series with the resistance through which current was measured

The brightness of two 100 Watt light bulbs in series connected to a 110 V is ____ compared to a single 100 Watt light bulb connected to a 110 V power outlet. Greater Lesser Equal Random

Lesser

The brightness of two 100 Watt light bulbs in parallel connected to a 110 V is ____ compared to a single 100 Watt light bulb connected to a 110 V power outlet. Greater Lesser Equal Random

Greater

What is the potential drop within a battery that has an internal resistance of 4 ohms when a current of 2 amperes passes through it? ``` 4 V 2 V 8 V 8.000 V 8 mV ```

8 V

A potential drop of 8 V within the battery of internal resistance R when current of 2 ampere passes through it indicates that R equals ``` 4 V 4 ohms 4 A 16 ohms R = 8/2 = 4 ohms/mA 4 mA ```

4 ohms

A potential drop of 8 V within the battery of internal resistance 4 ohms when current I ampere passes through it indicates that I equals ``` 2 V 2 ohms 2 A 32 ohms 32 A ```

2 A

0.50 A current generates 4.18 W of power while passing through a resistance. Find the resistance. 17 ohms 16. 72 watts 16. 7 ohms 16. 7 volts 8. 4 ohms

17 ohms

A current generates 6000. Watts of power while passing through a 1500. ohms resistance. Find the current. 2. 000 A 2. 0 A 2. 0 W 4. 000 mA 4. 000 A

2.000 A

A 25 mA current passes through a 150. ohms resistance. Find the voltage across the resistance. 3.75 mV 3750. V 3750 V 3.75 V 3.8 V

3.8 V

A current passes through a 1500. ohms resistance. The voltage across the resistance is 55 V. Find the current. 27.2727 A 27.273 27 mA 37 mA 37 A

37 mA

A 100. mA current passes through a resistance. The voltage across the resistance is 55 V. Find the resistance. 0.55 Kilo Ohm 1500. Ohm C. 1500 Mega Ohm D. 1.8 Ohm E. 1.82 Ohm

0.55 Kilo Ohm

A typical body resistance for a dry human being is about 1 M Ohm (1 million Ohms). If such a person becomes a path to ground across a potential difference of 1000 volts will the electric shock be fatal? HINT: 500 mA (one-half of Ampere) is considered a deadly current. Yes because the delivered current is greater than 0.5 A Yes because the delivered current equals 1 mA No because the current delivered is only 1 mA No because the current delivered is greater than 1 mA Yes because the current delivered is less than 500 mA

No because the current delivered is only 1 mA

A 75 watt light bulb operates on regular house voltage of 120 volts. Normal current in the light bulb is 0.625 amperes. What is the resistance of the light bulb filament (the wire that glows). Use the same equation for the average values as for the instantaneous ones. ``` 225 ohms 1.6 ohms 120 ohms 192 ohms 190 ohms ```

190 ohms

An electric circuit consists of a 12 volt battery connected across a resistance of 2 ohms in series with a resistance of 4 ohms. What is the current delivered to the circuit? ``` zero amperes 1 amperes 2 amperes 9 amperes 7.2 amperes ```

2 amperes

A 10.0 ohm resistance is connected in series with a parallel combination of two 10.0 ohm resistances. What is the combined resistance of the circuit? 30.0 ohms 20.0 ohms 15.0 ohms 10.0 ohms 15 ohms

15.0 ohms

Given the following symbols: RT = Total Combined Resistance; R1 = 10 ohms. If R1, R2, and R3 are connected in parallel, what is the value of RT? ``` 5.00 ohms 40 ohms 20 ohms 10. ohms 5 ohms ```

5 ohms

If you buy an automobile storage battery rated at 45 ampere*hour, the battery will deliver 45 amperes for a period of 45 hours store 1.6E5 coulombs of charge deliver 16E5 coulombs of charge per second last 45 hours deliver 1.6E5 amperes

store 1.6E5 coulombs of charge

If 6.00 coulombs move in a electric circuit every 2 seconds, what is the magnitude of the average current? ``` 3 A 0.333 A 12 A 18 A 1.5 A ```

3 A

A 75 watt light bulb operates on regular house voltage. Normal average current in the light bulb is 0.625 A. Find the average voltage. Use the same equation for average values as for instantaneous ones. (P=IV) ``` 120 V 220 V 120. V 220. V 60 V ```

120 V

A 75 watt light bulb operates on regular house voltage of 120 volts. Find the normal average current in the light bulb filament. Use the same equation for average values as for instantaneous ones. (P=IV) 0. 625 A 0. 63 A 1. 6 A 0. 625 mA 0. 63 mA

0.63 A

A circuit is wired with a power supply, a resistor and a ammeter (for measuring current). The ammeter reads a current of 24 mA (milliAmps). Determine the new current if the voltage of the power supply was held constant and the resistance was increased by a factor of 4. ``` Inew = 6 mA Inew = 48 mA Inew = 72 mA Inew = 12 mA ```

Inew = 6 mA

Lab 4 Flashcards

(50 cards)