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

\(\text{Total time (to aircraft and back)} = 4 \times 10^{-3} \, \text{s} \) \(\text{Speed of radio waves} = 3 \times 10^8 \, \text{m/s}\) \(\text{Round-trip distance} = 3 \times 10^8 \times 4 \times 10^{-3}\) = 1.2 \(\times 10^6 \, \text{m}\) \(\text{Actual distance to aircraft} = \frac{1.2 \times 10^6}{2}\) = 600,000m = 600km.

F = \(\frac{r}{2}\) and v = mu F = \(\frac{UV}{U + V}\) \(\frac{r}{2}\) = \(\frac{U \times mu}{U + mu}\) \(\frac{r}{2}\) = \(\frac{mu^2}{u(1 + m)}\) \(\frac{r}{2} = \frac{mu}{1+m}\) \(\frac{r}{2} = \frac{v}{1+m}\) \(\frac{2v}{r} = 1+m\) \(m = \frac{2v}{r} - 1\)

F = \(\frac{uv}{u + v}\) 20 = \(\frac{100 \times v}{100 + v}\) v = 25cm

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

\(\frac{4}{3}\) = \(\frac{sin30}{sinr}\) r = 22oC

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

Soft iron is more readily magnetized than steel (i): Soft iron can become magnetized more easily and reaches saturation quicker than steel. Soft iron is more readily demagnetized than steel (ii): Soft iron loses its magnetism more quickly when the magnetic field is removed, which is desirable in applications like electromagnets that need to be turned on and off. Soft iron retains magnetism more than steel (iii): Soft iron does not retain magnetism as well as steel; that is one of the reasons it is used in electromagnets. Therefore, i and ii are correct.

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

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

E = 4 + 2r and E = 2 + 3r therefore, r = 2\(\Omega\)

Q = it = 100 x 10-3 x 2 x 60 = 12C

C = \(\frac {\varepsilon_o\ A}{d}\) 10-2 x 10-6 = \(\frac {9 \times 10 ^{-12}}{d}\) x 10-4 = 9 x 10-7m

P = \(\frac{V}{R}\) V = \(\sqrt{PR}\) V = \(\sqrt{40 \times 90}\) = 60V

An induction coil is a transformer for producing high-voltage alternating current from a low-voltage direct current, consisting essentially of two concentric coils with a common soft-iron core, a primary coil with relatively few windings of heavy wire, and a secondary coil with many turns of fine wire. Excitation of the primary coil by rapidly interrupted or variable current induces high voltage in the secondary coil.