A vertical wire carries a current in an upward direction. An electron beam sent horizontally towards the wire will be deflected 

1.   towards right

2.   towards left 

3.   upwards

4.   downwards

A moving charge produces:

The magnetic field at the origin due to a current element \(i\vec{dl}\) placed at a position \(\vec r\) is
(a). \(\frac{\mu_{0} i_{}{}}{4 \pi} \frac{d\vec{l} \times \vec{r}}{r^{3}}\)
(b). \(-\frac{\mu_{0} i_{}{}}{4 \pi} \frac{\vec{r} \times d\vec{l}}{r^{3}}\)
(c). \(\frac{\mu_{0} i_{}{}}{4 \pi} \frac{\vec{r} \times d\vec{l}}{r^{3}}\)
(d). \(-\frac{\mu_{0} i_{}{}}{4 \pi} \frac{d\vec{l} \times \vec{r}}{r^{3}}\)

Choose the correct option: 
1. (a), (b)
2. (b), (c)
3. (c), (d)
4. (a), (d)