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2 years ago

Which one of the following statements concerning emf is true?

Physics

1 answer:

Andrej [43]2 years ago

3 0

Answer:

C) Emf is the force exerted on a single charge to move it from one terminal to the other of an emf device.

Explanation:

Electromotive force, abbreviation E or emf, electrical energy per unit supplied from an energy source, such as an electrical generator or a battery. In the engine or battery, electricity is transformed from one source to another as the device works on the electrical charge that is passed within itself.

In physics it is defined as Work done by a cell or battery in moving a unit charge from its one terminal to the other, against the potential.

Hence C is correct

You might be interested in

How far can a person run in 15 minutes if he runs at an average speed of 16 km/hr?

anygoal [31]

Answer:

4km

Explanation:

15 minutes is 1/4 of an hour.

1/4 of 16 is 4.

3 0

3 years ago

A body which has surface area 5cm² and temperature of 727°C radiates 300J of energy in one minute. Calculate it's emissivity giv

cestrela7 [59]

<h2>Answer: 0.17</h2>

Explanation:

The Stefan-Boltzmann law establishes that a black body (an ideal body that absorbs or emits all the radiation that incides on it) "emits thermal radiation with a total hemispheric emissive power proportional to the fourth power of its temperature":

$P=\sigma A T^{4}$ (1)

Where:

$P=300J/min=5J/s=5W$ is the energy radiated by a blackbody radiator per second, per unit area (in Watts). Knowing $1W=\frac{1Joule}{second}=1\frac{J}{s}$

$\sigma=5.6703(10)^{-8}\frac{W}{m^{2} K^{4}}$ is the Stefan-Boltzmann's constant.

$A=5cm^{2}=0.0005m^{2}$ is the Surface area of the body

$T=727\°C=1000.15K$ is the effective temperature of the body (its surface absolute temperature) in Kelvin.

However, there is no ideal black body (ideal radiator) although the radiation of stars like our Sun is quite close. So, in the case of this body, we will use the Stefan-Boltzmann law for real radiator bodies:

$P=\sigma A \epsilon T^{4}$ (2)

Where $\epsilon$ is the body's emissivity

(the value we want to find)

Isolating $\epsilon$ from (2):

$\epsilon=\frac{P}{\sigma A T^{4}}$ (3)

Solving:

$\epsilon=\frac{5W}{(5.6703(10)^{-8}\frac{W}{m^{2} K^{4}})(0.0005m^{2})(1000.15K)^{4}}$ (4)

Finally:

$\epsilon=0.17$ (5) This is the body's emissivity

3 0

2 years ago

Which of the following represent units of capacitance? You may choose more than one correct answer:

inessss [21]

Answer:

Capacitance is a derived physical quantity measured in farad

4 0

2 years ago

How can a small spark start a huge explosion? using electric forces and molecules

OLga [1]

Answer:

Small sparks can lead to huge explosion if they are left unattended.

Explanation:

Small sparks are not harmful but if these sparks happen near some hazardous material or object then it could lead to heavy explosion. If there is some chemical substance near the spark or there are magnetic lines which can explode the spark then these minor sparks could result in heavy disastrous explosion.

4 0

2 years ago

Calculate the volume of this regular solid.

Nataly [62]

Answer:

V = 42.41cm^3

Explanation:

In order to calculate the volume of the solid, you use the following formula:

$V=\frac{1}{3}\pi r^2 h$

where

r: radius of the circular base of the cone = 3 cm

h: height from the circular base to the peak of the cone = 4.5 cm

You replace the values of r and h in the formula for the volume V:

$V=\frac{1}{3}\pi(3cm)^2(4.5)=42.411cm^3\approx42.41cm^3$

hence, the volume of the solid is 42.41 cm^3

5 0

2 years ago