the potential difference across the terminals of electric heater is 60v and it draws a current 4A what current current it draws when potential d

The question is partially typed. So assuming that the potential difference have increased to120 V below is the solution for it- 

V= 60V

I = 4A

R= V/I =60/4= 15 ohms

Resistance of electric heater is 15 ohms 

Now if the Potential difference is increased to 120 V ( if there is any other value  of potential difference you can substitite in place of 120 and calculate in similar way  as given below) 

I= 120/ 15 = 8 A