Physics

• Why doesn't nuclear fusion occur at low temperatures?

  Due to electrostatic repulsion of protons
• What unit is used for moment in physics?

  Newton metre (Nm)
• What is the relationship between moment and distance from the pivot?

  Moment = force × perpendicular distance
• Where does the weight of a body act?

  Through its centre of gravity
• What principle is used for parallel forces in one plane?

  Principle of moments
• How do upward forces on a beam vary?

  With the position of a heavy object
• What units are used for light waves?

  Degree, hertz, metre, second
• What type of waves are light waves?

  Transverse waves
• What is the law of reflection?

  Angle of incidence equals angle of reflection
• How can ray diagrams illustrate reflection and refraction?

  By showing angles and paths of light
• How can the refraction of light be investigated practically?

  Using blocks and prisms
• What is the relationship between refractive index and angles?

  n = sin i / sin r
• How can the refractive index of glass be investigated?

  Using a glass block
• What role does total internal reflection play?

  Transmits information in optical fibres
• What is the relationship between critical angle and refractive index?

  sin c = 1 / n
• How can all waves be manipulated?

  They can be reflected and refracted
• What is the electromagnetic spectrum?

  Continuous spectrum including various radiations
• What is the relationship between speed, frequency, and wavelength in electromagnetic waves?

  Wave speed = frequency × wavelength
• What types of radiation are included in the electromagnetic spectrum?

  Radio, microwave, infrared, visible, ultraviolet, x-ray, gamma
• What are some uses of electromagnetic radiations?

  Broadcasting, cooking, medical imaging