M. Yassin PHYSICS Electricity and Radioactivity A/AS Part 1

Thorium-234 (234 Th) decays by β– emission into a daughter product which in turn decays by a 90

further β– emission into a granddaughter product.
Which letter in the diagram represents the granddaughter product?

• A

• B

• C

• D

37. A nucleus of magnesium decays into a nucleus of sodium by emitting a β⁺ particle. The decay is represented by the equation shown.

• P : 22

  Q : 11

• P : 22

  Q : 13

• P : 23

  Q : 11

• P : 23

  Q : 13

37. A sample of an isotope emits β^- particles.
    The emitted β^- particles have a range of energies.

    What must also be emitted?

• 37. antineutrinos

• 37. neutrinos

• 37. antineutrons

• 37. neutrons

37. The battery of a car has an internal resistance of 0.10 Ω and an electromotive force of 12 V. When the battery is connected to the starter motor, the potential difference across the battery terminals is 7.0 V.

    What is the current supplied to the starter motor?

• 37. 50 A

• 37. 70 A

• 37. 120 A

• 37. 190 A

35. In deriving a formula for the combined resistance of three different resistors in series, Kirchhoff’s laws are used.

    Which physics principle is involved in this derivation?

• 1. the conservation of charge

• 1. the direction of the flow of charge is from negative to positive

• 1. the potential difference across each resistor is the same

• 1. the current varies in each resistor, in proportion to the resistor value

35. Three resistors, each of resistance R, are connected in a network, as shown.

36. The total resistance between points X and Y is 8.0 Ω.
    What is the value of R ?
    

• 35. 2.7 Ω

• 35. 4.0 Ω

• 35. 5.3 Ω

• 35. 12 Ω

Three cells with e.m.f.s V₁, V₂ and V₃, have negligible internal resistance. These cells are connected to three resistors with resistances R₁, R₂ and R₃, as shown.

The current in the circuit is I.

Which equation is correct?

• V₁ + V₂ + V₃ = I (R₁ + R₂ + R₃)

• V₁ + V₂ - V₃ = I (R₁ + R₂ + R₃)

• V₁ - V₂ + V₃ = I (R₁ + R₂ + R₃)

• V₁ - V₂ - V₃ = I (R₁ + R₂ + R₃)

30. A 12 V battery is charged for 20 minutes by connecting it to a source of electromotive force (e.m.f.). The battery is supplied with 7.2 × 10⁴ J of energy in this time.

    How much charge flows through the battery?

• 30. 5.0 C

• 30. 60 C

• 30. 100 C

• 30. 6000 C

30. Which measurements are taken in order to calculate the resistivity of the metal of a piece of wire?

• 1. p.d., current, area, length

• 1. p.d., current, diameter, length

• 1. resistance, area, length

• 1. resistance, length, radius

30. A fixed resistor of resistance 12 Ω is connected to a battery. There is a current of 0.20 A in the

    resistor. The current is now doubled.

    What is the new power dissipated in the resistor?

• 30. 0.48 W

• 30. 0.96 W

• 30. 1.92 W

• 30. 4.8 W