00. Biot-Savart's Law and Magnetic Field, Lorentz Force
Moving Charges & Magnetism

153277 A straight conductor of length $l$ carrying a current, $I$, is bent in the form of a semicircle. The magnetic field (in tesla) at the centre of the semicircle is:

1 $\frac{\pi^{2} \mathrm{I}}{l} \times 10^{-7}$
2 $\frac{\pi \mathrm{I}}{l} \times 10^{-7}$
3 $\frac{\pi \mathrm{I}}{l^{2}} \times 10^{-7}$
4 $\frac{\pi \mathrm{I}^{2}}{l} \times 10^{-7}$
5 $\frac{\pi \mathrm{I}^{2}}{l^{2}} \times 10^{-7}$
Moving Charges & Magnetism

153278 Two circular coils $C$ and $D$ have equal number of turns and carry equal currents in the same direction in the same sense and subtend same solid angle at point $O$ as shown in figure. The smaller coil $C$ is midway between $O$ and $D$. If we represent magnetic field induction due to bigger coil and smaller coil $C$ as $B_{D}$ and $B_{C}$ respectively, then $B_{D} / B_{C}$ is

1 $1: 4$
2 $1: 2$
3 $2: 1$
4 $1: 1$
Moving Charges & Magnetism

153280 Two parallel long wires carry currents $i_{1}$ and $i_{2}$ with $i_{1}>i_{2}$. When the currents are in the same direction, the magnetic field midway between the wires is $10 \mu \mathrm{T}$. When the direction of $i_{2}$ is reversed, it becomes $40 \mu \mathrm{T}$. Then, ratio of $i_{1} / i_{2}$ is

1 $3: 4$
2 $5: 3$
3 $7: 11$
4 $11: 7$
Moving Charges & Magnetism

153281 A straight wire of mass $200 \mathrm{~g}$ and length $1.5 \mathrm{~m}$ carries a current of $2 \mathrm{~A}$. It is suspended in midair by a uniform horizontal magnetic field $B$. The magnitude of $B$ (in tesla) is (assume $\mathrm{g}=9.8 \mathrm{~ms}^{-2}$ )

1 2
2 1.5
3 0.55
4 0.65
Moving Charges & Magnetism

153282 A wire carrying current, $1 \mathrm{~A}$ is shaped as shown Magnetic flux density at $O$ is

1 $\frac{5 \mu_{0}}{4 \pi}$, inwards
2 $\frac{5 \mu_{0}}{4 \pi}$, outwards
3 $\frac{5 \mu_{0}}{4}$, inwards
4 $\frac{5 \mu_{0}}{4}$, outwards
Moving Charges & Magnetism

153277 A straight conductor of length $l$ carrying a current, $I$, is bent in the form of a semicircle. The magnetic field (in tesla) at the centre of the semicircle is:

1 $\frac{\pi^{2} \mathrm{I}}{l} \times 10^{-7}$
2 $\frac{\pi \mathrm{I}}{l} \times 10^{-7}$
3 $\frac{\pi \mathrm{I}}{l^{2}} \times 10^{-7}$
4 $\frac{\pi \mathrm{I}^{2}}{l} \times 10^{-7}$
5 $\frac{\pi \mathrm{I}^{2}}{l^{2}} \times 10^{-7}$
Moving Charges & Magnetism

153278 Two circular coils $C$ and $D$ have equal number of turns and carry equal currents in the same direction in the same sense and subtend same solid angle at point $O$ as shown in figure. The smaller coil $C$ is midway between $O$ and $D$. If we represent magnetic field induction due to bigger coil and smaller coil $C$ as $B_{D}$ and $B_{C}$ respectively, then $B_{D} / B_{C}$ is

1 $1: 4$
2 $1: 2$
3 $2: 1$
4 $1: 1$
Moving Charges & Magnetism

153280 Two parallel long wires carry currents $i_{1}$ and $i_{2}$ with $i_{1}>i_{2}$. When the currents are in the same direction, the magnetic field midway between the wires is $10 \mu \mathrm{T}$. When the direction of $i_{2}$ is reversed, it becomes $40 \mu \mathrm{T}$. Then, ratio of $i_{1} / i_{2}$ is

1 $3: 4$
2 $5: 3$
3 $7: 11$
4 $11: 7$
Moving Charges & Magnetism

153281 A straight wire of mass $200 \mathrm{~g}$ and length $1.5 \mathrm{~m}$ carries a current of $2 \mathrm{~A}$. It is suspended in midair by a uniform horizontal magnetic field $B$. The magnitude of $B$ (in tesla) is (assume $\mathrm{g}=9.8 \mathrm{~ms}^{-2}$ )

1 2
2 1.5
3 0.55
4 0.65
Moving Charges & Magnetism

153282 A wire carrying current, $1 \mathrm{~A}$ is shaped as shown Magnetic flux density at $O$ is

1 $\frac{5 \mu_{0}}{4 \pi}$, inwards
2 $\frac{5 \mu_{0}}{4 \pi}$, outwards
3 $\frac{5 \mu_{0}}{4}$, inwards
4 $\frac{5 \mu_{0}}{4}$, outwards
Moving Charges & Magnetism

153277 A straight conductor of length $l$ carrying a current, $I$, is bent in the form of a semicircle. The magnetic field (in tesla) at the centre of the semicircle is:

1 $\frac{\pi^{2} \mathrm{I}}{l} \times 10^{-7}$
2 $\frac{\pi \mathrm{I}}{l} \times 10^{-7}$
3 $\frac{\pi \mathrm{I}}{l^{2}} \times 10^{-7}$
4 $\frac{\pi \mathrm{I}^{2}}{l} \times 10^{-7}$
5 $\frac{\pi \mathrm{I}^{2}}{l^{2}} \times 10^{-7}$
Moving Charges & Magnetism

153278 Two circular coils $C$ and $D$ have equal number of turns and carry equal currents in the same direction in the same sense and subtend same solid angle at point $O$ as shown in figure. The smaller coil $C$ is midway between $O$ and $D$. If we represent magnetic field induction due to bigger coil and smaller coil $C$ as $B_{D}$ and $B_{C}$ respectively, then $B_{D} / B_{C}$ is

1 $1: 4$
2 $1: 2$
3 $2: 1$
4 $1: 1$
Moving Charges & Magnetism

153280 Two parallel long wires carry currents $i_{1}$ and $i_{2}$ with $i_{1}>i_{2}$. When the currents are in the same direction, the magnetic field midway between the wires is $10 \mu \mathrm{T}$. When the direction of $i_{2}$ is reversed, it becomes $40 \mu \mathrm{T}$. Then, ratio of $i_{1} / i_{2}$ is

1 $3: 4$
2 $5: 3$
3 $7: 11$
4 $11: 7$
Moving Charges & Magnetism

153281 A straight wire of mass $200 \mathrm{~g}$ and length $1.5 \mathrm{~m}$ carries a current of $2 \mathrm{~A}$. It is suspended in midair by a uniform horizontal magnetic field $B$. The magnitude of $B$ (in tesla) is (assume $\mathrm{g}=9.8 \mathrm{~ms}^{-2}$ )

1 2
2 1.5
3 0.55
4 0.65
Moving Charges & Magnetism

153282 A wire carrying current, $1 \mathrm{~A}$ is shaped as shown Magnetic flux density at $O$ is

1 $\frac{5 \mu_{0}}{4 \pi}$, inwards
2 $\frac{5 \mu_{0}}{4 \pi}$, outwards
3 $\frac{5 \mu_{0}}{4}$, inwards
4 $\frac{5 \mu_{0}}{4}$, outwards
Moving Charges & Magnetism

153277 A straight conductor of length $l$ carrying a current, $I$, is bent in the form of a semicircle. The magnetic field (in tesla) at the centre of the semicircle is:

1 $\frac{\pi^{2} \mathrm{I}}{l} \times 10^{-7}$
2 $\frac{\pi \mathrm{I}}{l} \times 10^{-7}$
3 $\frac{\pi \mathrm{I}}{l^{2}} \times 10^{-7}$
4 $\frac{\pi \mathrm{I}^{2}}{l} \times 10^{-7}$
5 $\frac{\pi \mathrm{I}^{2}}{l^{2}} \times 10^{-7}$
Moving Charges & Magnetism

153278 Two circular coils $C$ and $D$ have equal number of turns and carry equal currents in the same direction in the same sense and subtend same solid angle at point $O$ as shown in figure. The smaller coil $C$ is midway between $O$ and $D$. If we represent magnetic field induction due to bigger coil and smaller coil $C$ as $B_{D}$ and $B_{C}$ respectively, then $B_{D} / B_{C}$ is

1 $1: 4$
2 $1: 2$
3 $2: 1$
4 $1: 1$
Moving Charges & Magnetism

153280 Two parallel long wires carry currents $i_{1}$ and $i_{2}$ with $i_{1}>i_{2}$. When the currents are in the same direction, the magnetic field midway between the wires is $10 \mu \mathrm{T}$. When the direction of $i_{2}$ is reversed, it becomes $40 \mu \mathrm{T}$. Then, ratio of $i_{1} / i_{2}$ is

1 $3: 4$
2 $5: 3$
3 $7: 11$
4 $11: 7$
Moving Charges & Magnetism

153281 A straight wire of mass $200 \mathrm{~g}$ and length $1.5 \mathrm{~m}$ carries a current of $2 \mathrm{~A}$. It is suspended in midair by a uniform horizontal magnetic field $B$. The magnitude of $B$ (in tesla) is (assume $\mathrm{g}=9.8 \mathrm{~ms}^{-2}$ )

1 2
2 1.5
3 0.55
4 0.65
Moving Charges & Magnetism

153282 A wire carrying current, $1 \mathrm{~A}$ is shaped as shown Magnetic flux density at $O$ is

1 $\frac{5 \mu_{0}}{4 \pi}$, inwards
2 $\frac{5 \mu_{0}}{4 \pi}$, outwards
3 $\frac{5 \mu_{0}}{4}$, inwards
4 $\frac{5 \mu_{0}}{4}$, outwards
Moving Charges & Magnetism

153277 A straight conductor of length $l$ carrying a current, $I$, is bent in the form of a semicircle. The magnetic field (in tesla) at the centre of the semicircle is:

1 $\frac{\pi^{2} \mathrm{I}}{l} \times 10^{-7}$
2 $\frac{\pi \mathrm{I}}{l} \times 10^{-7}$
3 $\frac{\pi \mathrm{I}}{l^{2}} \times 10^{-7}$
4 $\frac{\pi \mathrm{I}^{2}}{l} \times 10^{-7}$
5 $\frac{\pi \mathrm{I}^{2}}{l^{2}} \times 10^{-7}$
Moving Charges & Magnetism

153278 Two circular coils $C$ and $D$ have equal number of turns and carry equal currents in the same direction in the same sense and subtend same solid angle at point $O$ as shown in figure. The smaller coil $C$ is midway between $O$ and $D$. If we represent magnetic field induction due to bigger coil and smaller coil $C$ as $B_{D}$ and $B_{C}$ respectively, then $B_{D} / B_{C}$ is

1 $1: 4$
2 $1: 2$
3 $2: 1$
4 $1: 1$
Moving Charges & Magnetism

153280 Two parallel long wires carry currents $i_{1}$ and $i_{2}$ with $i_{1}>i_{2}$. When the currents are in the same direction, the magnetic field midway between the wires is $10 \mu \mathrm{T}$. When the direction of $i_{2}$ is reversed, it becomes $40 \mu \mathrm{T}$. Then, ratio of $i_{1} / i_{2}$ is

1 $3: 4$
2 $5: 3$
3 $7: 11$
4 $11: 7$
Moving Charges & Magnetism

153281 A straight wire of mass $200 \mathrm{~g}$ and length $1.5 \mathrm{~m}$ carries a current of $2 \mathrm{~A}$. It is suspended in midair by a uniform horizontal magnetic field $B$. The magnitude of $B$ (in tesla) is (assume $\mathrm{g}=9.8 \mathrm{~ms}^{-2}$ )

1 2
2 1.5
3 0.55
4 0.65
Moving Charges & Magnetism

153282 A wire carrying current, $1 \mathrm{~A}$ is shaped as shown Magnetic flux density at $O$ is

1 $\frac{5 \mu_{0}}{4 \pi}$, inwards
2 $\frac{5 \mu_{0}}{4 \pi}$, outwards
3 $\frac{5 \mu_{0}}{4}$, inwards
4 $\frac{5 \mu_{0}}{4}$, outwards