Chapters 16, 17, & 18, and 22, 23, & 24 - Electric Current and Light

Question 1

What is Ohm’s Law? Equation?

Answer 1

Current is proportional to a change in voltage.

Current = Voltage/Resistance

Question 2

Units for Ohm’s Law:
- Current
- Voltage
- Resistance

Answer 2

Current is measured in Amperes (amps)
Voltage is measured in Volts
Resistance is measured in Ohms

Question 3

What is electrical resistance?

Answer 3

The ratio of the potential difference (or voltage) across a conductor to the current (I) through the material

Question 4

Name the 4 things that change the resistance of circuits

Answer 4

1) Temperature
2) Material
3) Size
4) Shape

Question 5

What is electric potential?

Answer 5

Electric potential energy per unit of charge.

Question 6

When something gets wet, what happens to its resistance?

Answer 6

When something gets wet, its resistance is lowered and electrical current can travel through it much faster. That’s why we have to dry off any sweat before doing Estim so it won’t shock/burn the patient.

Question 7

What range of amps (electric current) is safe when doing estim?

Answer 7

1mA - 5mA is safe and normal. Anything higher than than would cause muscle contractions, burns, paralysis, and death.

Question 8

What direction will electricity flow?

Answer 8

Always flows from areas of high electrical PE to Low electrical PE.

For a positive charge, lower potential energy means lower potential
For a negative charged, lower potential energy means higher potential

Question 9

Components of the electromagnetic spectrum?

Answer 9

oscillating electric and magnetic fields

Question 10

Which travel faster, infrared waves or UV rays?

Answer 10

All waves on the electromagnetic spectrum travel at the same speed. Only the wavelength and frequency change.

Question 11

What happens to frequency and wavelength as you move from infrared to gamma waves on the electromagnetic spectrum?

Answer 11

Infrared waves have a long wavelength and a low frequency. As you move along to UV and gamma rays, the waves have a shorter wavelength and a higher frequency.

Question 12

What particles are responsible for electric conductivity?

Answer 12

Electrons transport electric charge through a material. The more free-floating electrons a material has, the greater its conductivity.

Question 13

What flows through a circuit? What causes the circuit to flow in the first place?

Answer 13

Charge is what flows through a circuit. There has to be a potential difference in the circuit in order for charge to flow.

Question 14

Function of rods in the eye?

Answer 14

Rods are responsible for black-and-white vision in your periphery.

Question 15

Function of cones in the eye?

Answer 15

Cones are responsible for color in the central part of your vision

Question 16

What happens to the pupil of the eye when you are happy? What about when you are sad?

Answer 16

The pupil dilates (up to 55%) when you are happy, and constricts when you are sad.

Question 17

What is a potential difference?

Answer 17

The change in electric PE per unit of charge

Question 18

What is electric potential energy?

Answer 18

The energy stored in an electric field

Question 19

Which subatomic particles conduct electricity?

Answer 19

Electrons conduct electricity but protons do not.

Question 20

What happens to resistance when a material is stretched thinner?

Answer 20

If you stretch a material so it is thinner, the resistance between its ends will increase.

Question 21

What happens to resistance as temperature increases?

Answer 21

Resistance increases as temperature increases.

Question 22

What is the retina?

Answer 22

• located at the back of the eyeball
• contains rods and cones