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Total Resistance R = 1/R = 1/R1 + 1/R2 + 1/R3 R = 12/13Ω V = IR = (12/13) x 13 = 12v 1 across 3Ω = V/R = 12/3 = 4A

No expanded working has been attached for this question yet. The verified answer is Option D.

R/30 = 100/150R = 20Ω

F = qE; E = F/q = 40/(1.0 x 10-5) = 4.0 x 106

R = V2/P = 2402/40 = 1440Ω

A bird remains safe on a single wire because it has only one point of contact, keeping it at a single electrical potential. However, if the bird touches another object with a different potential, it would complete a path to the ground, resulting in severe electric shock or electrocution.

I = E/R + r = 1.5/2.5 + 0.5 + 7 = 0.15

This is a description of the d.c electric motor. The coil rotates due to the interaction between the magnetic field and the current flowing through the coil. The split ring and brushes act as a commutator, reversing the current direction in the coil every half rotation to maintain continuous rotation.

Ivt = mcΔθ t = mcΔθ/Iv = 3x 4200 x (88 - 28)/6 x 200

i) The back e.m.f. generated in the primary coil of an induction coil opposes the flow of current in the coil, causing a decrease in the current. This effect can be reduced by using a capacitor in the circuit, which stores the charge and releases it when the current drops. This maintains the flow of current and reduces the effect of the back e.m.f. ii) The make-and-break contact in the circuit also helps to reduce the effect of the back e.m.f. The contact repeatedly breaks the circuit, causing the current to stop flowing momentarily, which interrupts the magnetic field and reduces the back e.m.f.

No expanded working has been attached for this question yet. The verified answer is Option E.

No expanded working has been attached for this question yet. The verified answer is Option B.

I: Energy is required to remove electrons (ionization energy). II & III: Nucleus particles (protons & neutrons) are held by the strong nuclear force, so separating them requires large energy. IV: In uranium fission, released energy comes from the mass defect (mass of products < mass of original nucleus) via E = mc\(^2\)

No expanded working has been attached for this question yet. The verified answer is Option C.

(a) Fission: Nuclear reaction in which a heavy nucleus is bombarded with neutrons and split into approximate equal parts emitting neutrons and releasing large amounts of energy. Fusion: Nuclear reaction between two light nuclei forming a heavier nucleus with the release of a large amount of energy. (b) Advantages of Fusion over Fission: (1)By - products are non-radioactive. (2) Easily achieved with lightest elements so that nuclear repulsion is easily overcome as nuclei approach each other. (3) Raw materials are cheaply available. Why fusion is not normally used : Very high temperature is required to overcome coulomb repulsive forces between the two light nuclei. It is difficult to get materials that will withstand such high temperature. Mathematically, \(T^{\frac{1}{2}} = \frac{0.693}{\lambda}\), where \(\lambda\) is the decay constant. Decay constant = \(\frac{\text{no of atoms disintegrating per sec}}{\text{no of atoms in the source at that instant}}\) Isotopes: Isotopes of an element are atoms which have the same proton numbers/atoms number but different nucleon numbers/mass number. Decay scheme: \(^{238} _{92} U \to ^{234} _{90} Th + ^{4} _{2} He + Energy\) \(^{234} _{90} Th \to ^{234} _{91} Pa + ^{0} _{-1} e + Energy\) \(^{234} _{91} \to ^{0} _{-1} e + ^{234} _{92} + Energy\) (d) Uses of radioisotopes: (1) Radio therapy (2) Radio dating (3) Used as tracers and preservatives in agriculture.