Matric Physics: Basic Electronics, questions with answers

Answer: C. All inputs are LOW

OR output is 0 only when every input is 0.

Answer: B. NOR

NOT (A OR B) is the NOR gate.

Answer: A. Electrical signals

A CRO displays and measures voltages (electrical signals) against time.

Answer: D. A = 0, B = 0

NOR = NOT (A OR B); it is 1 only when both inputs are 0.

Answer: B. OR

In parallel, the bulb lights if either switch (or both) is closed — an OR gate. Switches in series act as AND.

(a) Electric field: between two parallel plates the electron beam is deflected towards the positive plate, following a curved (parabolic) path while inside the field and then travelling in a straight line — like a projectile.
(b) Magnetic field: when the beam enters a uniform magnetic field perpendicular to its motion it experiences a force perpendicular to its velocity (F = Bev) and moves in a circular arc; the direction of deflection is given by Fleming's left‑hand rule (remembering that electron current is opposite to conventional current).

Cathode rays are streams of fast‑moving electrons, so they carry negative charge.
Electric field: when passed between two charged plates they are deflected towards the positive plate, showing they are negatively charged.
Magnetic field: when a magnetic field is applied perpendicular to the beam they are deflected in a circular path according to Fleming's left‑hand rule (treating the electron beam as a current flowing in the opposite direction). These deflections are used in CRO/TV tubes.

Analogue electronics deals with signals that vary continuously with time and can take any value within a range (e.g. the output of a microphone, a mercury thermometer, a moving‑coil meter). Digital electronics deals with signals that have only two discrete levels, 0 and 1 (low/high voltage), processed by logic gates (e.g. computers, digital watches, calculators). Digital signals are less affected by noise, easier to store and process, and can be copied without loss.