JEE Mains · Physics · STD 12 - 1. Electric charges and fields
Two point charges \(A\) and \(B\) of magnitude \(+8 \times 10^{-6}\,C\) and \(-8 \times 10^{-6}\,C\) respectively are placed at a distance \(d\) apart. The electric field at the middle point \(O\) between the charges is \(6.4 \times 10^{4}\,NC ^{-1}\). The distance ' \(d\) ' between the point charges \(A\) and \(B\) is..............\(m\)
- A \(2.0\)
- B \(3.0\)
- C \(1.0\)
- D \(4.0\)
Answer & Solution
Correct Answer
(B) \(3.0\)
Step-by-step Solution
Detailed explanation
\(E _{0}=2 \times \frac{ Kq }{( d / 2)^{2}}\) \(\Rightarrow E _{0}=8 \frac{ Kq }{ d ^{2}}\) \(\Rightarrow d ^{2}=\frac{8 \times 9 \times 10^{9} \times 8 \times 10^{-6}}{6.4 \times 10^{4}}\) \(d =3\,m\)
See the Complete Solution
Get step-by-step explanations for this and 2.5 Lakh+ more JEE, NEET & CET questions.
- Unlock all solutions
- Practice the full chapter
- Track accuracy across PYQs
4.8 rated on Google Play · 14,000+ reviews
More questions from Physics
- A wheatstone bridge is initially at room temperature and all arms of the bridge have same value of resistances ( \(R_1=R_2=R_3=R_4\) ). When \(R_3\) resistance is heated to some temperature, its resistance value has gone up by \(10 \%\). The potential difference \(\left( V _{ a }- V _{ b }\right)\) (after \(R _3\) is heated) is ___________ V.
JEE Mains 2026 Easy - Two bodies of masses \(m_{1}=5\,kg\) and \(m _{2}=3\,kg\) are connected by a light string going over a smooth light pulley on a smooth inclined plane as shown in the figure. The system is at rest. The force exerted by the inclined plane on the body of mass \(m _{1}\) will be\(....N\) [Take \(g=10\,ms ^{-2}\) ]
JEE Mains 2022 Hard - Suppose that intensity of a laser is \(\left(\frac{315}{\pi}\right)\, W / m ^{2} .\) The \(rms\) electric field, in units of \(V / m\) associated with this source is close to the nearest integer is \(\left(\epsilon_{0}=8.86 \times 10^{-12} C ^{2} Nm ^{-2} ; c =3 \times 10^{8} ms ^{-1}\right)\)JEE Mains 2020 Medium
- Moment of inertia of a dise of mass \(M\) and radius ' \(R\) ' about any of its diameter is \(\frac{ MR ^2}{4}\). The moment of inertia of this disc about an axis normal to the disc and passing through a point on its edge will be, \(\frac{ x }{2} MR ^2\). The value of \(x\) is \(..........\).JEE Mains 2023 Medium
- The temperature, at which the root mean square velocity of hydrogen molecules equals their escape velocity from the earth is closest to : [Boltzmans Constant \(k_B = 1.38\times10^{-23}\, J / K\) Avogadro number \(N_A = 6.02\times10^{26}\, / kg\) Radius of Earth \(: 6.4\times10^6\, m\) Gravitation acceleration on Earth \(= 10\, ms^{-2}\)]JEE Mains 2019 Medium
- Two coils of self inductance \(L _{1}\) and \(L _{2}\) are connected in series combination having mutual inductance of the coils as \(M\). The equivalent self inductance of the combination will be ...............
JEE Mains 2022 Medium
More PYQs from JEE Mains
- Let\(\int \frac{2-\tan x}{3+\tan x} d x=\frac{1}{2}\left(\alpha x+\log _e|\beta \sin x+\gamma \cos x|\right)+C\), where \(\mathrm{C}\) is the constant of integration. Then \(\alpha+\frac{\gamma}{\beta}\) is equal to :JEE Mains 2024 Hard
- Let \(\vec a = 2\hat i - \hat j + \hat k\), \(\vec b = \hat i + 2\hat j - \hat k\) and \(\vec c = \hat i + \hat j - 2\hat k\) be three vectors. A vector of the type \(\vec b + \lambda \vec c\) for some scalar \(\lambda \), whose projection on \(\vec a\) is of magnitude \(\sqrt {\frac{2}{3}} \) isJEE Mains 2013 Hard
- A simple pendulum made of a bob of mass \(m\) and a metallic wire of negligible mass has time period \(2s\) at \(T = 0\,^oC\) . If the temeprature of the wire is increased and the corresponding change in its time peirod is plotted against its temperature, the resulting graph is a line of slope \(S\). If the coefficient of linear expansion of metal is \(\alpha \) then the value of \(S\) isJEE Mains 2016 Hard
- An observer looks at a distant tree of height \(10\ m\) with a telescope of magnifying power of \(20\). To the observer the tree appears :JEE Mains 2016 Easy
- Two wires each of radius \(0.2\,cm\) and negligible mass, one made of steel and other made of brass are loaded as shown in the figure. The elongation of the steel wire is \(.........\times 10^{-6}\,m\). [Young's modulus for steel \(=2 \times 10^{11}\,Nm ^{-2}\) and \(g =10\,ms ^{-2}\) ]
JEE Mains 2023 Hard - Let a plane \(P\) contain two lines \(\overrightarrow{ r }=\hat{ i }+\lambda(\hat{ i }+\hat{ j }), \lambda \in R\) and \(\overrightarrow{ r }=-\hat{j}+\mu(\hat{j}-\hat{ k }), \mu \in R\) If \(Q (\alpha, \beta, \gamma)\) is the foot of the perpendicular drawn from the point \(M (1,0,1)\) to \(P ,\) then \(3(\alpha+\beta+\gamma)\) equalsJEE Mains 2020 Hard