有current一定有voltage?

有current一定有voltage?
有potential difference所以有current

有voltage一定有current?
有potential difference，如果之間無circuit，無current

有induced current一定有induced voltage?
有induced e.m.f.所以有induced current

有induced voltage一定有induced current?
有induced e.m.f.，如果之間無circuit，無induced current