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Esthetician (NIC Theory Exam) · Scientific Concepts

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Esthetician (NIC Theory Exam) Hair, Electricity, and Safety Summary

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About 11 of 55 Scientific Concepts questions (20%)

Hair structure and growth, electrical basics, and safe use of equipment and chemicals.

📖 See Hair, Electricity, and Safety concepts →

Hair, Electricity, and Safety: must-know points

  • A hair has three layers: cuticle, cortex, and medulla.
  • The growth cycle is anagen (growth), catagen (transition), and telogen (rest).
  • A volt measures pressure, an ampere measures current, and an ohm measures resistance.
  • A Safety Data Sheet (SDS) explains a chemical's hazards and handling.

Hair, Electricity, and Safety: 10 sample questions

Practice questionReviewedScientific Concepts › Hair, Electricity, and Safety★★★★☆

Question 1. What protein is hair mostly made of?

  1. ① Melanin
  2. ② Elastin
  3. ③ Sebum
  4. ④ Keratin
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Answer: ④ Keratin

Key point: Hair is made of keratin

Hair, skin, and nails are made mostly of the tough protein keratin.

Wrong choices

  • Melanin: Melanin is pigment inside hair.
  • Elastin: Elastin is stretchy fibre in the dermis.
  • Sebum: Sebum is oil.
Practice questionReviewedScientific Concepts › Hair, Electricity, and Safety★★★★☆

Question 2. Which phase of the hair growth cycle is the active growing phase?

  1. ① Anagen
  2. ② Catagen
  3. ③ Telogen
  4. ④ Papilla
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Answer: ① Anagen

Key point: Anagen = growth

In anagen the cells of the bulb divide and the hair grows longer.

Wrong choices

  • Catagen: Catagen is the short transition phase.
  • Telogen: Telogen is the resting phase.
  • Papilla: The papilla is a structure, not a phase.
Practice questionReviewedScientific Concepts › Hair, Electricity, and Safety★★★★☆

Question 3. What does a volt measure?

  1. ① The strength of the current
  2. ② Electrical pressure
  3. ③ Resistance
  4. ④ The power used
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Answer: ② Electrical pressure

Key point: Volt = electrical pressure

The volt measures the force that pushes current through a wire.

Wrong choices

  • The strength of the current: Current strength is measured in amperes.
  • Resistance: Resistance is measured in ohms.
  • The power used: Power is measured in watts.
Practice questionReviewedScientific Concepts › Hair, Electricity, and Safety★★★★☆

Question 4. What is the outermost layer of the hair strand?

  1. ① The cuticle
  2. ② The cortex
  3. ③ The medulla
  4. ④ The bulb
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Answer: ① The cuticle

Key point: Cuticle = outer layer

The cuticle is made of overlapping scales that protect the hair.

Wrong choices

  • The cortex: The cortex is the middle layer.
  • The medulla: The medulla is the center, and some fine hair has none.
  • The bulb: The bulb is at the root.
Practice questionReviewedScientific Concepts › Hair, Electricity, and Safety★★★☆☆

Question 5. Which part of the follicle feeds the growing hair with blood?

  1. ① The arrector pili
  2. ② The sebaceous gland
  3. ③ The dermal papilla
  4. ④ The hair shaft
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Answer: ③ The dermal papilla

Key point: Papilla feeds the hair

The dermal papilla sits at the base of the follicle and holds blood vessels that supply the hair bulb.

Wrong choices

  • The arrector pili: The arrector pili is a tiny muscle.
  • The sebaceous gland: The sebaceous gland makes oil.
  • The hair shaft: The shaft is the part above the skin.
Practice questionReviewedScientific Concepts › Hair, Electricity, and Safety★★★☆☆

Question 6. Which tiny muscle makes the hair stand up when you are cold or scared?

  1. ① The frontalis
  2. ② The masseter
  3. ③ The platysma
  4. ④ The arrector pili
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Answer: ④ The arrector pili

Key point: Arrector pili = goosebumps

The arrector pili is attached to the follicle and pulls the hair upright, causing goosebumps.

Wrong choices

  • The frontalis: The frontalis raises the eyebrows.
  • The masseter: The masseter helps chew.
  • The platysma: The platysma is a neck muscle.
Practice questionReviewedScientific Concepts › Hair, Electricity, and Safety★★★☆☆

Question 7. What is a material that does not easily let electricity flow?

  1. ① A conductor
  2. ② A rectifier
  3. ③ An insulator
  4. ④ A converter
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Answer: ③ An insulator

Key point: Insulator blocks current

Rubber, plastic, and glass are insulators. Cords are covered in them for safety.

Wrong choices

  • A conductor: A conductor lets electricity flow easily.
  • A rectifier: A rectifier changes AC to DC.
  • A converter: A converter changes the type of current.
Practice questionReviewedScientific Concepts › Hair, Electricity, and Safety★★★☆☆

Question 8. Which layer of the hair contains most of the pigment and gives strength?

  1. ① The cuticle
  2. ② The medulla
  3. ③ The cortex
  4. ④ The papilla
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Answer: ③ The cortex

Key point: Cortex holds pigment

The cortex is the thick middle layer. It holds most of the melanin and gives the hair strength and elasticity.

Wrong choices

  • The cuticle: The cuticle is the outer scale layer.
  • The medulla: The medulla is the center core.
  • The papilla: The papilla is at the base of the follicle.
Practice questionReviewedScientific Concepts › Hair, Electricity, and Safety★★★☆☆

Question 9. Which phase is the short transition phase when the hair bulb shrinks away from the papilla?

  1. ① Catagen
  2. ② Anagen
  3. ③ Telogen
  4. ④ Lanugo
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Answer: ① Catagen

Key point: Catagen = transition

In catagen, growth stops and the follicle shrinks. Telogen follows.

Wrong choices

  • Anagen: Anagen is active growth.
  • Telogen: Telogen is the resting phase.
  • Lanugo: Lanugo is fine hair on a fetus.
Practice questionReviewedScientific Concepts › Hair, Electricity, and Safety★★★☆☆

Question 10. Which is NOT a safe practice when using electrical equipment?

  1. ① Checking cords for damage
  2. ② Keeping cords away from water
  3. ③ Touching a device with wet hands
  4. ④ Unplugging equipment when finished
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Answer: ③ Touching a device with wet hands

Key point: Never touch electrical devices with wet hands

Water conducts electricity, so wet hands raise the risk of shock. The other practices lower risk.

Wrong choices

  • Checking cords for damage: Checking cords is a safe practice.
  • Keeping cords away from water: Keeping cords away from water is a safe practice.
  • Unplugging equipment when finished: Unplugging when done is a safe practice.

Test yourself.

Hair, Electricity, and Safety: 5 questions →Scientific Concepts: 5 questions →