Identify the correct statements among the following:
(A) A moving charge creates a magnetic field in the space surrounding it.
(B) The magnetic field can exert a force on a moving charge.
(C) The magnetic force can be maximum when a charged particle moves along the magnetic field.
(D) A charged particle can pass undeflected in a crossed field (E x B) configuration.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → (A), (B) and (D) only
The magnetic force on a moving charge, \( F = qvB\sin\theta \), depends on the angle between the velocity and the field.
(A) A moving charge creates a magnetic field in the space surrounding it. — Correct. A moving charge is a current element and produces a magnetic field.
(B) The magnetic field can exert a force on a moving charge. — Correct. The force is non-zero whenever the velocity is not along the field.
(C) The magnetic force can be maximum when a charged particle moves along the magnetic field. — Incorrect. Along the field \( \theta = 0^\circ \), so \( F = 0 \); the force is maximum when the motion is perpendicular to the field.
(D) A charged particle can pass undeflected in a crossed field (E x B) configuration. — Correct. The electric and magnetic forces cancel when \( qE = qvB \), that is, for \( v = E/B \) (the velocity selector).
Note: Statements (A), (B) and (C) of this question are from the latest textbook (2026-27). Statement (D), that a charged particle passes undeflected through crossed electric and magnetic fields (the velocity selector), is printed only in the pre-rationalised textbook (2022-23). It was removed from the latest book, but the force on a moving charge in uniform magnetic and electric fields is still in the CUET 2026 syllabus, so do not skip it.
NCERT (2026-27):
Sources and Fields – “… Just as static charges produce an electric field, the currents or moving charges produce (in addition) a magnetic field, denoted by B (r), again a vector field.”
Magnetic Field, Lorentz Force – “… The force on an electric charge q due to both of them can be written as
\( \displaystyle \mathbf{F} = q\,[\,\mathbf{E}(\mathbf{r}) + \mathbf{v} \times \mathbf{B}(\mathbf{r})\,] \equiv \mathbf{F}_{electric} + \mathbf{F}_{magnetic} \qquad (4.3) \)”
Magnetic Field, Lorentz Force – “… (ii) The magnetic force q [ v × B ] includes a vector product of velocity and magnetic field. The vector product makes the force due to magnetic field vanish (become zero) if velocity and magnetic field are parallel or anti-parallel.”
NCERT (Pre-rationalised edition, 2022-23):
Velocity Selector – “… The crossed E and B fields, therefore, serve as a velocity selector. Only particles with speed E/B pass undeflected through the region of crossed fields.”