Question 1

Which of the following statement most accurately describes Ohm's Law?&#10;A) The current flowing through a conductor is proportional to the voltage across that conductor&#10;B) The current flowing through a conductor is equal to the voltage across that conductor, divided by its resistance&#10;C) The ratio of voltage to current is constant for variations in voltage

Accepted Answer

The ratio of voltage to current is constant for variations in voltage&#10;

Question 2

Not all materials or devices obey Ohm's Law. Those that do, are termed&#10;A) linear or ohmic&#10;B) non-linear or non-ohmic&#10;C) insulators&#10;D) electrolytes

Accepted Answer

Ohm's Law states that the current through a conductor between two points is directly proportional to the voltage across the two points. Materials or devices that obey this law are called linear or ohmic. Non-linear or non-ohmic materials or devices do not have a constant resistance and therefore do not obey Ohm's Law. Insulators and electrolytes are not directly related to Ohm's Law adherence.

Question 3

For those materials or devices that obey Ohm's Law, a graph of their voltage against current results in a&#10;A) straight-line graph&#10;B) non-linear graph

Accepted Answer

Ohm's Law states that the voltage across a material or device is directly proportional to the current passing through it, so a graph of voltage against current for these materials/devices will always result in a straight-line graph.

Question 4

The ratio of voltage to current represents the __________ of a material or device, regardless of whether or not it obeys Ohm's Law&#10;A) conductance&#10;B) resistance&#10;C) resistivity

Accepted Answer

The ratio of voltage to current in a material or device represents its resistance, which is a measure of how much it opposes the flow of electric current. This is true regardless of whether the material or device obeys Ohm's Law, which states that the current through a conductor between two points is directly proportional to the voltage across the two points. Resistance is a fundamental electrical property, distinct from conductance (which is the reciprocal of resistance) and resistivity (which is a material property reflecting how strongly a material opposes current flow).

Question 5

When a voltage of 12 V is applied across a resistance of 10 ohms, a current of 1.2 A results. Does this resistance obey Ohm's Law?&#10;A) yes&#10;B) no&#10;C) there is not enough information to tell

Accepted Answer

The answer of When a voltage of 12 V is...

Question 6

When a voltage of 200 V is applied across a circuit, the resulting current is 5 A. When the voltage is increased to 300 V, the resulting current is 7.5A. Does the circuit probably obey Ohm's Law?&#10;A) Yes, because the ratio of voltage to current remains constant for a change in voltage&#10;B) No, because a change in voltage results in a different value of current

Accepted Answer

The circuit likely obeys Ohm's Law because the ratio of voltage to current (V/I) remains constant (200V/5A = 40Ω and 300V/7.5A = 40Ω), indicating a linear relationship between voltage and current, which is a hallmark of Ohm's Law.

Question 7

Does a tungsten lamp filament obey Ohm's Law?&#10;A) Yes, because it is a pure metal conductor&#10;B) No, because its resistance increases significantly as the voltage applied across it increases

Accepted Answer

A tungsten lamp filament does not obey Ohm's Law because its resistance increases significantly with an increase in voltage applied across it. This is due to the phenomenon of joule heating, which causes the temperature of the filament to increase, leading to an increase in resistance. Therefore, the relationship between the voltage and current through the filament is not linear and cannot be described by a simple proportionality, as predicted by Ohm's Law.

Question 8

When a voltage of 15 V is applied to a resistance of 3 ohms, the resulting current is&#10;A) 0.333 A&#10;B) 5 A&#10;C) 45 A

Accepted Answer

Using Ohm's Law, which states that current (I) equals voltage (V) divided by resistance (R), we calculate the current as I = V/R = 15V / 3Ω = 5A.

Question 9

When a voltage of 200 V results in a current of 2.5 A, the resistance of circuit is&#10;A) 500 ohms&#10;B) 80 ohms&#10;C) 12.5 milliohms

Accepted Answer

The resistance (R) can be found using Ohm's Law:

V = IR

where V is voltage, I is current, and R is resistance.

Plugging in the given values:

200 V = 2.5 A x R

Solving for R:

R = 80 ohms

Therefore, the answer is B.

Question 10

When a current of 3 A passes through a resistance of 75 ohms, the voltage across that resistance must be&#10;A) 0.04 V&#10;B) 25 ohms&#10;C) 225 ohms

Accepted Answer

We can use Ohm's Law to determine the voltage across the resistance:

V = IR

V = (3 A)(75 ohms)

V = 225 V

Therefore, the voltage across the resistance is 225 volts.

Deck 7: Ohms Law of Constant Proportionality