Physical Quantity and Units

Which of the following is an SI base unit?

• current

• gram

• Kelvin

• volt

Which of the following pairs of units are both SI base units?

• ampere, degree celsius

• ampere, kelvin

• gram, degree celsius

• gram, kelvin

A student measures a current as 0.5A.

Which of the following correctly expresses this result?

• 50 mA

• 50 MA

• 500 mA

• 500 MA

The notation µs is used as an abbreviation for a certain unit of time.

What is the name and value of this unit?

• microsecond ,

  10^–6 s

• microsecond ,

  10^–3 s

• milisecond ,

  10^–6 s

• milisecond ,

  10^–3 s

When a beam of light is incident on a surface, it delivers energy to the surface.

The intensity of the beam is defined as the energy delivered per unit area per unit time.

What is the unit of intensity, expressed in SI base units?

• kg m^–2 s^–1

• kg m² s^–3

• kg s^–2

• kg s^–3

Which line of the table gives values that are equal to a time of 1 ps (one picosecond) and a distance of 1 Gm (one gigametre)?

• 10^–9 s ,

  10⁹ m

• 10^–9 s ,

  10¹² m

• 10^–12 s ,

  10⁹ m

• 10^–12 s ,

  10¹² m

Decimal sub-multiples and multiples of units are indicated using a prefix to the unit. For example, the prefix milli (m) represents 10–3.

Which of the following gives the sub-multiples or multiples represented by pico (p) and giga (G)?

• 10^–9 ,

  10⁹

• 10^–9 ,

  10¹²

• 10^–12 ,

  10⁹

• 10^–12 ,

  10¹²

Which product-pair of metric prefixes has the greatest magnitude?

• pico × mega

• nano × kilo

• micro × giga

• milli × tera

Which is a pair of SI base units?

• ampere,

  joule

• coulomb,

  second

• kilogram,

  kelvin

• metre,

  newton

Five energies are listed.

5 kJ

5 mJ

5 MJ

5 nJ

Starting with the smallest first, what is the order of increasing magnitude of these energies?

• 5 kJ → 5 mJ → 5 MJ → 5 nJ

• 5 nJ → 5 kJ → 5 MJ → 5 mJ

• 5 nJ → 5 mJ → 5 kJ → 5 MJ

• 5 mJ → 5 nJ → 5 kJ → 5 MJ